gmail-mcp

Projects that follow the best practices below can voluntarily self-certify and show that they've achieved an Open Source Security Foundation (OpenSSF) best practices badge.

There is no set of practices that can guarantee that software will never have defects or vulnerabilities; even formal methods can fail if the specifications or assumptions are wrong. Nor is there any set of practices that can guarantee that a project will sustain a healthy and well-functioning development community. However, following best practices can help improve the results of projects. For example, some practices enable multi-person review before release, which can both help find otherwise hard-to-find technical vulnerabilities and help build trust and a desire for repeated interaction among developers from different companies. To earn a badge, all MUST and MUST NOT criteria must be met, all SHOULD criteria must be met OR be unmet with justification, and all SUGGESTED criteria must be met OR unmet (we want them considered at least). If you want to enter justification text as a generic comment, instead of being a rationale that the situation is acceptable, start the text block with '//' followed by a space. Feedback is welcome via the GitHub site as issues or pull requests There is also a mailing list for general discussion.

We gladly provide the information in several locales, however, if there is any conflict or inconsistency between the translations, the English version is the authoritative version.
If this is your project, please show your badge status on your project page! The badge status looks like this: Badge level for project 12613 is silver Here is how to embed it:
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These are the Silver level criteria. You can also view the Passing or Gold level criteria.

Baseline Series: Baseline Level 1 Baseline Level 2 Baseline Level 3

        

 Basics 17/17 ●

  • General

    Note that other projects may use the same name.

    A Model Context Protocol (MCP) server for Gmail integration in Claude Desktop with auto authentication support. This server enables AI assistants to manage Gmail through natural language interactions.

    Please use SPDX license expression format; examples include "Apache-2.0", "BSD-2-Clause", "BSD-3-Clause", "GPL-2.0+", "LGPL-3.0+", "MIT", and "(BSD-2-Clause OR Ruby)". Do not include single quotes or double quotes.
    If there is more than one language, list them as comma-separated values (spaces optional) and sort them from most to least used. If there is a long list, please list at least the first three most common ones. If there is no language (e.g., this is a documentation-only or test-only project), use the single character "-". Please use a conventional capitalization for each language, e.g., "JavaScript".
    The Common Platform Enumeration (CPE) is a structured naming scheme for information technology systems, software, and packages. It is used in a number of systems and databases when reporting vulnerabilities.

  • Prerequisites


    Enough for a badge!

    The project MUST achieve a passing level badge. [achieve_passing]

  • Basic project website content


    Enough for a badge!

    The information on how to contribute MUST include the requirements for acceptable contributions (e.g., a reference to any required coding standard). (URL required) [contribution_requirements]

    CONTRIBUTING.md documents PR requirements (branch from main, conventional commit titles ≤72 chars, tests for new behaviour, CodeRabbit assertive review must approve before merge, respect the ESLint/Prettier config). URL: https://github.com/klodr/gmail-mcp/blob/main/CONTRIBUTING.md


  • Project oversight


    Barely enough for a badge.

    The project SHOULD have a legal mechanism where all developers of non-trivial amounts of project software assert that they are legally authorized to make these contributions. The most common and easily-implemented approach for doing this is by using a Developer Certificate of Origin (DCO), where users add "signed-off-by" in their commits and the project links to the DCO website. However, this MAY be implemented as a Contributor License Agreement (CLA), or other legal mechanism. (URL required) [dco]
    The DCO is the recommended mechanism because it's easy to implement, tracked in the source code, and git directly supports a "signed-off" feature using "commit -s". To be most effective it is best if the project documentation explains what "signed-off" means for that project. A CLA is a legal agreement that defines the terms under which intellectual works have been licensed to an organization or project. A contributor assignment agreement (CAA) is a legal agreement that transfers rights in an intellectual work to another party; projects are not required to have CAAs, since having CAA increases the risk that potential contributors will not contribute, especially if the receiver is a for-profit organization. The Apache Software Foundation CLAs (the individual contributor license and the corporate CLA) are examples of CLAs, for projects which determine that the risks of these kinds of CLAs to the project are less than their benefits.

    Solo-maintainer project. If adopted, the approach would be DCO via git commit --signoff plus a DCO probot gating PRs on main.


    Enough for a badge!

    The project MUST clearly define and document its project governance model (the way it makes decisions, including key roles). (URL required) [governance]
    There needs to be some well-established documented way to make decisions and resolve disputes. In small projects, this may be as simple as "the project owner and lead makes all final decisions". There are various governance models, including benevolent dictator and formal meritocracy; for more details, see Governance models. Both centralized (e.g., single-maintainer) and decentralized (e.g., group maintainers) approaches have been successfully used in projects. The governance information does not need to document the possibility of creating a project fork, since that is always possible for FLOSS projects.

    CONTINUITY.md documents the governance model (solo lead maintainer @klodr), handover pathway (public repo + MIT + Sigstore-signed releases → any party can fork and resume), takeover checklist with concrete steps, and contact (GitHub profile). No opaque decision-making surface. URL: https://github.com/klodr/gmail-mcp/blob/main/CONTINUITY.md


    Enough for a badge!

    The project MUST adopt a code of conduct and post it in a standard location. (URL required) [code_of_conduct]
    Projects may be able to improve the civility of their community and to set expectations about acceptable conduct by adopting a code of conduct. This can help avoid problems before they occur and make the project a more welcoming place to encourage contributions. This should focus only on behavior within the community/workplace of the project. Example codes of conduct are the Linux kernel code of conduct, the Contributor Covenant Code of Conduct, the Debian Code of Conduct, the Ubuntu Code of Conduct, the Fedora Code of Conduct, the GNOME Code Of Conduct, the KDE Community Code of Conduct, the Python Community Code of Conduct, The Ruby Community Conduct Guideline, and The Rust Code of Conduct.

    https://github.com/klodr/gmail-mcp/blob/main/CODE_OF_CONDUCT.md


    Enough for a badge!

    The project MUST clearly define and publicly document the key roles in the project and their responsibilities, including any tasks those roles must perform. It MUST be clear who has which role(s), though this might not be documented in the same way. (URL required) [roles_responsibilities]
    The documentation for governance and roles and responsibilities may be in one place.

    CONTINUITY.md defines two roles — Lead maintainer (@klodr: accepts/merges PRs, publishes releases, rotates signing keys, handles security advisories) and Contributor (anyone opening a PR; must pass CI + CodeRabbit review). The takeover checklist documents explicit hand-off responsibilities. URL: https://github.com/klodr/gmail-mcp/blob/main/CONTINUITY.md


    Enough for a badge!

    The project MUST be able to continue with minimal interruption if any one person dies, is incapacitated, or is otherwise unable or unwilling to continue support of the project. In particular, the project MUST be able to create and close issues, accept proposed changes, and release versions of software, within a week of confirmation of the loss of support from any one individual. This MAY be done by ensuring someone else has any necessary keys, passwords, and legal rights to continue the project. Individuals who run a FLOSS project MAY do this by providing keys in a lockbox and a will providing any needed legal rights (e.g., for DNS names). (URL required) [access_continuity]

    CONTINUITY.md "Built-in resilience" + "Within 1 week of confirmed unavailability" sections document the concrete continuity plan. FLOSS guarantees (public MIT source, Sigstore-signed releases, SLSA attestations, npm provenance) mean any motivated party can fork and continue maintenance; no organisational lock-in, every secret and external service can be re-provisioned by a new maintainer within hours. User-side state (OAuth refresh token at ~/.gmail-mcp/credentials.json) is local, so a handover does not strand any centralised state. URL: https://github.com/klodr/gmail-mcp/blob/main/CONTINUITY.md


    Barely enough for a badge.

    The project SHOULD have a "bus factor" of 2 or more. (URL required) [bus_factor]
    A "bus factor" (aka "truck factor") is the minimum number of project members that have to suddenly disappear from a project ("hit by a bus") before the project stalls due to lack of knowledgeable or competent personnel. The truck-factor tool can estimate this for projects on GitHub. For more information, see Assessing the Bus Factor of Git Repositories by Cosentino et al.

    Bus factor is currently 1 (solo maintainer). This is disclosed openly in CONTINUITY.md. Mitigation: the repo is fully public, every release artifact is Sigstore-signed with public transparency-log entries (Rekor), so any motivated party could fork and resume maintenance without privileged access. Inviting a co-maintainer is an open invitation in CONTRIBUTING.md.


  • Documentation


    Enough for a badge!

    The project MUST have a documented roadmap that describes what the project intends to do and not do for at least the next year. (URL required) [documentation_roadmap]
    The project might not achieve the roadmap, and that's fine; the purpose of the roadmap is to help potential users and contributors understand the intended direction of the project. It need not be detailed.

    https://github.com/klodr/gmail-mcp#roadmap


    Enough for a badge!

    The project MUST include documentation of the architecture (aka high-level design) of the software produced by the project. If the project does not produce software, select "not applicable" (N/A). (URL required) [documentation_architecture]
    A software architecture explains a program's fundamental structures, i.e., the program's major components, the relationships among them, and the key properties of these components and relationships.

    ASSURANCE_CASE.md §2 "Trust boundaries" includes the architecture diagram (MCP client ↔ MCP server ↔ Gmail API) with the local FS jail layout; §3 "Secure-design principles applied" documents the per-component design; README "Why this MCP?" comparison table exhaustively describes the feature surface by capability (core Gmail surface, OAuth/authorization, security input handling, MCP protocol, publishing/discoverability, supply-chain integrity, CI/CD hardening, operational). URL: https://github.com/klodr/gmail-mcp/blob/main/ASSURANCE_CASE.md#2-trust-boundaries


    Enough for a badge!

    The project MUST document what the user can and cannot expect in terms of security from the software produced by the project (its "security requirements"). (URL required) [documentation_security]
    These are the security requirements that the software is intended to meet.

    SECURITY.md enumerates the security model (OAuth scope filtering, attachment + download jails, O_NOFOLLOW, Zod bounds, CRLF sanitization, crypto MIME boundary), what the MCP does NOT protect against, vulnerability reporting via GitHub security advisories with 48h acknowledgment target, and release verification via Sigstore/SLSA/npm provenance. ASSURANCE_CASE.md provides the threat model and CWE/OWASP mitigation table. URL: https://github.com/klodr/gmail-mcp/blob/main/SECURITY.md


    Enough for a badge!

    The project MUST provide a "quick start" guide for new users to help them quickly do something with the software. (URL required) [documentation_quick_start]
    The idea is to show users how to get started and make the software do anything at all. This is critically important for potential users to get started.

    README ## Installation and ## Configuration sections give a one-command npx -y @klodr/gmail-mcp quick start plus per-client setup (Claude Desktop, Claude Code, Cursor, Continue, OpenClaw). llms-install.md mirrors the guide in a format an LLM assistant can read to install on the user's behalf. URL: https://github.com/klodr/gmail-mcp#installation


    Enough for a badge!

    The project MUST make an effort to keep the documentation consistent with the current version of the project results (including software produced by the project). Any known documentation defects making it inconsistent MUST be fixed. If the documentation is generally current, but erroneously includes some older information that is no longer true, just treat that as a defect, then track and fix as usual. [documentation_current]
    The documentation MAY include information about differences or changes between versions of the software and/or link to older versions of the documentation. The intent of this criterion is that an effort is made to keep the documentation consistent, not that the documentation must be perfect.

    Every change is documented in CHANGELOG.md (Keep-a-Changelog format, semver). README revisions happen in the same PR as the code change they document; the README-consistency check in CI (.github/workflows/ci.yml) fails if the tool count in README diverges from the actual schema list in src/tools.ts.


    Enough for a badge!

    The project repository front page and/or website MUST identify and hyperlink to any achievements, including this best practices badge, within 48 hours of public recognition that the achievement has been attained. (URL required) [documentation_achievements]
    An achievement is any set of external criteria that the project has specifically worked to meet, including some badges. This information does not need to be on the project website front page. A project using GitHub can put achievements on the repository front page by adding them to the README file.

    README hero block displays all active badges — CI, CodeQL, Vitest, codecov, OpenSSF Scorecard, OpenSSF Best Practices (12613), Socket Security, CodeRabbit reviews, npm version/downloads, Node.js version, license, MCP version, sponsor links. Badges link out to live status pages so a visitor can see real-time state. URL: https://github.com/klodr/gmail-mcp


  • Accessibility and internationalization


    Enough for a badge!

    The project (both project sites and project results) SHOULD follow accessibility best practices so that persons with disabilities can still participate in the project and use the project results where it is reasonable to do so. [accessibility_best_practices]
    For web applications, see the Web Content Accessibility Guidelines (WCAG 2.0) and its supporting document Understanding WCAG 2.0; see also W3C accessibility information. For GUI applications, consider using the environment-specific accessibility guidelines (such as Gnome, KDE, XFCE, Android, iOS, Mac, and Windows). Some TUI applications (e.g. `ncurses` programs) can do certain things to make themselves more accessible (such as `alpine`'s `force-arrow-cursor` setting). Most command-line applications are fairly accessible as-is. This criterion is often N/A, e.g., for program libraries. Here are some examples of actions to take or issues to consider:
    • Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language ( WCAG 2.0 guideline 1.1)
    • Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. ( WCAG 2.0 guideline 1.4.1)
    • The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for large text, incidental text, and logotypes ( WCAG 2.0 guideline 1.4.3)
    • Make all functionality available from a keyboard (WCAG guideline 2.1)
    • A GUI or web-based project SHOULD test with at least one screen-reader on the target platform(s) (e.g. NVDA, Jaws, or WindowEyes on Windows; VoiceOver on Mac & iOS; Orca on Linux/BSD; TalkBack on Android). TUI programs MAY work to reduce overdraw to prevent redundant reading by screen-readers.

    This project is a headless MCP server (stdio JSON-RPC); it has no user-facing UI. Accessibility best practices for persons with disabilities do not apply at this layer — the consuming MCP client (Claude Desktop, Cursor, etc.) owns that surface.


    Enough for a badge!

    The software produced by the project SHOULD be internationalized to enable easy localization for the target audience's culture, region, or language. If internationalization (i18n) does not apply (e.g., the software doesn't generate text intended for end-users and doesn't sort human-readable text), select "not applicable" (N/A). [internationalization]
    Localization "refers to the adaptation of a product, application or document content to meet the language, cultural and other requirements of a specific target market (a locale)." Internationalization is the "design and development of a product, application or document content that enables easy localization for target audiences that vary in culture, region, or language." (See W3C's "Localization vs. Internationalization".) Software meets this criterion simply by being internationalized. No localization for another specific language is required, since once software has been internationalized it's possible for others to work on localization.

    The MCP emits tool descriptions and error strings in English for consumption by an LLM. Localization is owned by the client UI layer, not by the protocol-level tool surface.


  • Other


    Enough for a badge!

    If the project sites (website, repository, and download URLs) store passwords for authentication of external users, the passwords MUST be stored as iterated hashes with a per-user salt by using a key stretching (iterated) algorithm (e.g., Argon2id, Bcrypt, Scrypt, or PBKDF2). If the project sites do not store passwords for this purpose, select "not applicable" (N/A). [sites_password_security]
    Note that the use of GitHub meets this criterion. This criterion only applies to passwords used for authentication of external users into the project sites (aka inbound authentication). If the project sites must log in to other sites (aka outbound authentication), they may need to store authorization tokens for that purpose differently (since storing a hash would be useless). This applies criterion crypto_password_storage to the project sites, similar to sites_https.

    The project does not operate any website that stores user credentials. OAuth is delegated to Google; the only at-rest secret is the user's own refresh token, stored locally in ~/.gmail-mcp/credentials.json with mode 0o600.


 Change Control 1/1 ●

  • Previous versions


    Enough for a badge!

    The project MUST maintain the most often used older versions of the product or provide an upgrade path to newer versions. If the upgrade path is difficult, the project MUST document how to perform the upgrade (e.g., the interfaces that have changed and detailed suggested steps to help upgrade). [maintenance_or_update]

    The project follows semver. Breaking changes bump the major version; the CHANGELOG.md documents every breaking change under ### Changed (BREAKING). Users can pin to a specific semver range in their package.json; older majors remain installable from npm indefinitely thanks to npm's immutability guarantee. The current back-port policy (sole maintainer: no formal back-port) is disclosed in CONTRIBUTING.md.


 Reporting 3/3 ●

  • Bug-reporting process


    Enough for a badge!

    The project MUST use an issue tracker for tracking individual issues. [report_tracker]

    GitHub Issues is the public tracker. URL: https://github.com/klodr/gmail-mcp/issues


  • Vulnerability report process


    Enough for a badge!

    The project MUST give credit to the reporter(s) of all vulnerability reports resolved in the last 12 months, except for the reporter(s) who request anonymity. If there have been no vulnerabilities resolved in the last 12 months, select "not applicable" (N/A). (URL required) [vulnerability_report_credit]

    Credit policy is documented in SECURITY.md — reporters are acknowledged in the CHANGELOG entry that ships the fix unless they request anonymity. The GitHub security advisories workflow provides the private channel and tracks credit on the published advisory. URL: https://github.com/klodr/gmail-mcp/blob/main/SECURITY.md


    Enough for a badge!

    The project MUST have a documented process for responding to vulnerability reports. (URL required) [vulnerability_response_process]
    This is strongly related to vulnerability_report_process, which requires that there be a documented way to report vulnerabilities. It also related to vulnerability_report_response, which requires response to vulnerability reports within a certain time frame.

    SECURITY.md documents the private reporting channel (GitHub security advisories), the triage SLA (acknowledgment within 48h, fix/mitigation plan within 7 days for High/Critical), and the disclosure policy. URL: https://github.com/klodr/gmail-mcp/blob/main/SECURITY.md#reporting-a-vulnerability


 Quality 19/19 ●

  • Coding standards


    Enough for a badge!

    The project MUST identify the specific coding style guides for the primary languages it uses, and require that contributions generally comply with it. (URL required) [coding_standards]
    In most cases this is done by referring to some existing style guide(s), possibly listing differences. These style guides can include ways to improve readability and ways to reduce the likelihood of defects (including vulnerabilities). Many programming languages have one or more widely-used style guides. Examples of style guides include Google's style guides and SEI CERT Coding Standards.

    The project enforces the typescript-eslint recommendedTypeChecked preset plus opinionated add-ons (eqeqeq, no-console with narrow allowlist, type-aware unsafe rules). Formatting is Prettier with prettier --check in CI. CONTRIBUTING.md points contributors at both configs. URL: https://github.com/klodr/gmail-mcp/blob/main/eslint.config.js


    Enough for a badge!

    The project MUST automatically enforce its selected coding style(s) if there is at least one FLOSS tool that can do so in the selected language(s). [coding_standards_enforced]
    This MAY be implemented using static analysis tool(s) and/or by forcing the code through code reformatters. In many cases the tool configuration is included in the project's repository (since different projects may choose different configurations). Projects MAY allow style exceptions (and typically will); where exceptions occur, they MUST be rare and documented in the code at their locations, so that these exceptions can be reviewed and so that tools can automatically handle them in the future. Examples of such tools include ESLint (JavaScript), Rubocop (Ruby), and devtools check (R).

    CI runs npm run lint and npm run format:check on every push and every PR; branch protection on main blocks merge when either check fails. CodeRabbit (assertive profile) reviews each PR as a second enforcement layer. URL: https://github.com/klodr/gmail-mcp/blob/main/.github/workflows/ci.yml


  • Working build system


    Enough for a badge!

    Build systems for native binaries MUST honor the relevant compiler and linker (environment) variables passed in to them (e.g., CC, CFLAGS, CXX, CXXFLAGS, and LDFLAGS) and pass them to compiler and linker invocations. A build system MAY extend them with additional flags; it MUST NOT simply replace provided values with its own. If no native binaries are being generated, select "not applicable" (N/A). [build_standard_variables]
    It should be easy to enable special build features like Address Sanitizer (ASAN), or to comply with distribution hardening best practices (e.g., by easily turning on compiler flags to do so).

    Node.js project with a JavaScript/TypeScript toolchain (tsup bundler). CC/CFLAGS/CXX/CXXFLAGS/LDFLAGS are C/C++-toolchain variables; no native compilation happens in this build.


    Enough for a badge!

    The build and installation system SHOULD preserve debugging information if they are requested in the relevant flags (e.g., "install -s" is not used). If there is no build or installation system (e.g., typical JavaScript libraries), select "not applicable" (N/A). [build_preserve_debug]
    E.G., setting CFLAGS (C) or CXXFLAGS (C++) should create the relevant debugging information if those languages are used, and they should not be stripped during installation. Debugging information is needed for support and analysis, and also useful for measuring the presence of hardening features in the compiled binaries.

    tsup.config.ts emits source maps in dev (npm run dev) and suppresses them only in the published artifact (npm run build) to keep the npm tarball small. A user who needs debugging symbols can rebuild from source with tsup --sourcemap.


    Enough for a badge!

    The build system for the software produced by the project MUST NOT recursively build subdirectories if there are cross-dependencies in the subdirectories. If there is no build or installation system (e.g., typical JavaScript libraries), select "not applicable" (N/A). [build_non_recursive]
    The project build system's internal dependency information needs to be accurate, otherwise, changes to the project may not build correctly. Incorrect builds can lead to defects (including vulnerabilities). A common mistake in large build systems is to use a "recursive build" or "recursive make", that is, a hierarchy of subdirectories containing source files, where each subdirectory is independently built. Unless each subdirectory is fully independent, this is a mistake, because the dependency information is incorrect.

    Single-package repository. npm run build is a single invocation of tsup; there are no sub-builds with cross-dependencies.


    Enough for a badge!

    The project MUST be able to repeat the process of generating information from source files and get exactly the same bit-for-bit result. If no building occurs (e.g., scripting languages where the source code is used directly instead of being compiled), select "not applicable" (N/A). [build_repeatable]
    GCC and clang users may find the -frandom-seed option useful; in some cases, this can be resolved by forcing some sort order. More suggestions can be found at the reproducible build site.

    The release workflow pins Node version in the CI matrix, pins all GitHub Actions by full commit SHA, and pins package-lock.json for exact dependency resolution. tsup output is deterministic for a given input + config.


  • Installation system


    Enough for a badge!

    The project MUST provide a way to easily install and uninstall the software produced by the project using a commonly-used convention. [installation_common]
    Examples include using a package manager (at the system or language level), "make install/uninstall" (supporting DESTDIR), a container in a standard format, or a virtual machine image in a standard format. The installation and uninstallation process (e.g., its packaging) MAY be implemented by a third party as long as it is FLOSS.

    Installed via npm install -g @klodr/gmail-mcp or npx -y @klodr/gmail-mcp. Standard npm registry, standard install / uninstall semantics, no post-install hooks. URL: https://www.npmjs.com/package/@klodr/gmail-mcp


    Enough for a badge!

    The installation system for end-users MUST honor standard conventions for selecting the location where built artifacts are written to at installation time. For example, if it installs files on a POSIX system it MUST honor the DESTDIR environment variable. If there is no installation system or no standard convention, select "not applicable" (N/A). [installation_standard_variables]

    npm honors the standard npm config prefix + cache environment (NPM_CONFIG_PREFIX, npm_config_*). The project does not override these.


    Enough for a badge!

    The project MUST provide a way for potential developers to quickly install all the project results and support environment necessary to make changes, including the tests and test environment. This MUST be performed with a commonly-used convention. [installation_development_quick]
    This MAY be implemented using a generated container and/or installation script(s). External dependencies would typically be installed by invoking system and/or language package manager(s), per external_dependencies.

    git clone, npm ci, npm test — all documented in CONTRIBUTING.md. Under a minute on a system with Node 20.11+ already installed. URL: https://github.com/klodr/gmail-mcp/blob/main/CONTRIBUTING.md


  • Externally-maintained components


    Enough for a badge!

    The project MUST list external dependencies in a computer-processable way. (URL required) [external_dependencies]
    Typically this is done using the conventions of package manager and/or build system. Note that this helps implement installation_development_quick.

    package.json lists runtime and dev deps in machine-readable JSON. package-lock.json pins the full resolution tree with integrity hashes. Scorecard and Socket Security consume these directly in CI. URL: https://github.com/klodr/gmail-mcp/blob/main/package.json


    Enough for a badge!

    Projects MUST monitor or periodically check their external dependencies (including convenience copies) to detect known vulnerabilities, and fix exploitable vulnerabilities or verify them as unexploitable. [dependency_monitoring]
    This can be done using an origin analyzer / dependency checking tool / software composition analysis tool such as OWASP's Dependency-Check, Sonatype's Nexus Auditor, Synopsys' Black Duck Software Composition Analysis, and Bundler-audit (for Ruby). Some package managers include mechanisms to do this. It is acceptable if the components' vulnerability cannot be exploited, but this analysis is difficult and it is sometimes easier to simply update or fix the part.

    Dependabot scans weekly (npm + github-actions ecosystems), opens grouped PRs. Socket Security runs as a PR check on every dependency change. CodeQL Advanced (javascript-typescript + actions) runs on every push and every PR. Every alert is triaged inside the weekly review cycle. URL: https://github.com/klodr/gmail-mcp/blob/main/.github/dependabot.yml


    Enough for a badge!

    The project MUST either:
    1. make it easy to identify and update reused externally-maintained components; or
    2. use the standard components provided by the system or programming language.
    Then, if a vulnerability is found in a reused component, it will be easy to update that component. [updateable_reused_components]
    A typical way to meet this criterion is to use system and programming language package management systems. Many FLOSS programs are distributed with "convenience libraries" that are local copies of standard libraries (possibly forked). By itself, that's fine. However, if the program *must* use these local (forked) copies, then updating the "standard" libraries as a security update will leave these additional copies still vulnerable. This is especially an issue for cloud-based systems; if the cloud provider updates their "standard" libraries but the program won't use them, then the updates don't actually help. See, e.g., "Chromium: Why it isn't in Fedora yet as a proper package" by Tom Callaway.

    Dependencies are npm packages declared in package.json. Upgrading is npm install pkg@latest + rerun CI + merge. Dependabot automates the common case. No vendored copies, no forks with local patches.


    Enough for a badge!

    The project SHOULD avoid using deprecated or obsolete functions and APIs where FLOSS alternatives are available in the set of technology it uses (its "technology stack") and to a supermajority of the users the project supports (so that users have ready access to the alternative). [interfaces_current]

    Node floor is 20.11+. MCP SDK is on 1.29. googleapis tracks latest. zod is on v4 (supported by MCP SDK 1.29+). No deprecated Node APIs.


  • Automated test suite


    Enough for a badge!

    An automated test suite MUST be applied on each check-in to a shared repository for at least one branch. This test suite MUST produce a report on test success or failure. [automated_integration_testing]
    This requirement can be viewed as a subset of test_continuous_integration, but focused on just testing, without requiring continuous integration.

    Vitest suite (npm test, 120+ tests across 6 files including hardening.test.ts) runs on every push and every PR on a Node 20 / 22 / 24 matrix. URL: https://github.com/klodr/gmail-mcp/actions/workflows/ci.yml


    Enough for a badge!

    The project MUST add regression tests to an automated test suite for at least 50% of the bugs fixed within the last six months. [regression_tests_added50]

    Every security regression found during the hardening pass has a corresponding test in src/hardening.test.ts (23 tests covering crypto boundary, attachment jail, download jail, safeWriteFile symlink rejection, Zod bounds).


    Enough for a badge!

    The project MUST have FLOSS automated test suite(s) that provide at least 80% statement coverage if there is at least one FLOSS tool that can measure this criterion in the selected language. [test_statement_coverage80]
    Many FLOSS tools are available to measure test coverage, including gcov/lcov, Blanket.js, Istanbul, JCov, and covr (R). Note that meeting this criterion is not a guarantee that the test suite is thorough, instead, failing to meet this criterion is a strong indicator of a poor test suite.

    Coverage is measured by @vitest/coverage-v8 and uploaded to Codecov on the Node 20 CI job. Target is 80% statement coverage. URL: https://codecov.io/gh/klodr/gmail-mcp


  • New functionality testing


    Enough for a badge!

    The project MUST have a formal written policy that as major new functionality is added, tests for the new functionality MUST be added to an automated test suite. [test_policy_mandated]

    CONTRIBUTING.md requires tests for new behaviour; CodeRabbit's assertive profile flags PRs that change behaviour without touching a *.test.ts. URL: https://github.com/klodr/gmail-mcp/blob/main/CONTRIBUTING.md


    Enough for a badge!

    The project MUST include, in its documented instructions for change proposals, the policy that tests are to be added for major new functionality. [tests_documented_added]
    However, even an informal rule is acceptable as long as the tests are being added in practice.

    The PR review checklist in CONTRIBUTING.md and CodeRabbit's assertive profile together ensure every change proposal documents what was tested.


  • Warning flags


    Enough for a badge!

    Projects MUST be maximally strict with warnings in the software produced by the project, where practical. [warnings_strict]
    Some warnings cannot be effectively enabled on some projects. What is needed is evidence that the project is striving to enable warning flags where it can, so that errors are detected early.

    TypeScript strict: true in tsconfig.json. ESLint configured with recommendedTypeChecked plus no-console narrowed to error/warn only. CI fails on any ESLint error or TypeScript error.


 Security 13/13 ●

  • Secure development knowledge


    Enough for a badge!

    The project MUST implement secure design principles (from "know_secure_design"), where applicable. If the project is not producing software, select "not applicable" (N/A). [implement_secure_design]
    For example, the project results should have fail-safe defaults (access decisions should deny by default, and projects' installation should be secure by default). They should also have complete mediation (every access that might be limited must be checked for authority and be non-bypassable). Note that in some cases principles will conflict, in which case a choice must be made (e.g., many mechanisms can make things more complex, contravening "economy of mechanism" / keep it simple).

    ASSURANCE_CASE.md §3 enumerates the applied principles — least privilege (OAuth scope filtering, least-privilege permissions: in each workflow), defense in depth (Zod bounds + realpath + O_NOFOLLOW; Sigstore + SLSA + provenance), fail closed (missing keys → exit at startup; path outside jail → refuse; non-loopback callback → reject), minimise attack surface (single-file bundle, stdio only, tool list gated by scope), secrets env/local only, auditable & reproducible releases. URL: https://github.com/klodr/gmail-mcp/blob/main/ASSURANCE_CASE.md#3-secure-design-principles-applied


  • Use basic good cryptographic practices

    Note that some software does not need to use cryptographic mechanisms. If your project produces software that (1) includes, activates, or enables encryption functionality, and (2) might be released from the United States (US) to outside the US or to a non-US-citizen, you may be legally required to take a few extra steps. Typically this just involves sending an email. For more information, see the encryption section of Understanding Open Source Technology & US Export Controls.

    Enough for a badge!

    The default security mechanisms within the software produced by the project MUST NOT depend on cryptographic algorithms or modes with known serious weaknesses (e.g., the SHA-1 cryptographic hash algorithm or the CBC mode in SSH). [crypto_weaknesses]
    Concerns about CBC mode in SSH are discussed in CERT: SSH CBC vulnerability.

    The only crypto the project itself performs is crypto.randomBytes(16) for MIME boundary generation and SHA-256 for release artifact digests (Sigstore). No MD5, no SHA-1, no DES. TLS to Gmail uses Google's endpoints (TLS 1.2+ with modern cipher suites).


    Enough for a badge!

    The project SHOULD support multiple cryptographic algorithms, so users can quickly switch if one is broken. Common symmetric key algorithms include AES, Twofish, and Serpent. Common cryptographic hash algorithm alternatives include SHA-2 (including SHA-224, SHA-256, SHA-384 AND SHA-512) and SHA-3. [crypto_algorithm_agility]

    TLS negotiation is handled by Node's built-in TLS implementation, which supports algorithm agility at the protocol level. At-rest credentials are opaque (refresh token from Google); no algorithm choice at the MCP layer that would need agility.


    Enough for a badge!

    The project MUST support storing authentication credentials (such as passwords and dynamic tokens) and private cryptographic keys in files that are separate from other information (such as configuration files, databases, and logs), and permit users to update and replace them without code recompilation. If the project never processes authentication credentials and private cryptographic keys, select "not applicable" (N/A). [crypto_credential_agility]

    OAuth credentials live in ~/.gmail-mcp/credentials.json, completely separate from any project configuration file. No secrets live in package.json, .claude.json, or any checked-in file. URL: https://github.com/klodr/gmail-mcp/blob/main/SECURITY.md


    Enough for a badge!

    The software produced by the project SHOULD support secure protocols for all of its network communications, such as SSHv2 or later, TLS1.2 or later (HTTPS), IPsec, SFTP, and SNMPv3. Insecure protocols such as FTP, HTTP, telnet, SSLv3 or earlier, and SSHv1 SHOULD be disabled by default, and only enabled if the user specifically configures it. If the software produced by the project does not support network communications, select "not applicable" (N/A). [crypto_used_network]

    All network traffic is HTTPS to Google's Gmail API endpoints via the googleapis client. No plaintext HTTP.


    Enough for a badge!

    The software produced by the project SHOULD, if it supports or uses TLS, support at least TLS version 1.2. Note that the predecessor of TLS was called SSL. If the software does not use TLS, select "not applicable" (N/A). [crypto_tls12]

    googleapis uses Node's built-in fetch, which negotiates TLS 1.2 or TLS 1.3 with Google's endpoints. Google's endpoints refuse TLS <1.2 server-side.


    Enough for a badge!

    The software produced by the project MUST, if it supports TLS, perform TLS certificate verification by default when using TLS, including on subresources. If the software does not use TLS, select "not applicable" (N/A). [crypto_certificate_verification]
    Note that incorrect TLS certificate verification is a common mistake. For more information, see "The Most Dangerous Code in the World: Validating SSL Certificates in Non-Browser Software" by Martin Georgiev et al. and "Do you trust this application?" by Michael Catanzaro.

    Node's default TLS configuration performs full certificate-chain verification against the system trust store. The project does NOT override this. NODE_TLS_REJECT_UNAUTHORIZED=0 is never set by the project.


    Enough for a badge!

    The software produced by the project MUST, if it supports TLS, perform certificate verification before sending HTTP headers with private information (such as secure cookies). If the software does not use TLS, select "not applicable" (N/A). [crypto_verification_private]

    The OAuth bearer token is sent only after the TLS handshake completes. Node's fetch does not send the Authorization header until the TLS session is established and verified.


  • Secure release


    Enough for a badge!

    The project MUST cryptographically sign releases of the project results intended for widespread use, and there MUST be a documented process explaining to users how they can obtain the public signing keys and verify the signature(s). The private key for these signature(s) MUST NOT be on site(s) used to directly distribute the software to the public. If releases are not intended for widespread use, select "not applicable" (N/A). [signed_releases]
    The project results include both source code and any generated deliverables where applicable (e.g., executables, packages, and containers). Generated deliverables MAY be signed separately from source code. These MAY be implemented as signed git tags (using cryptographic digital signatures). Projects MAY provide generated results separately from tools like git, but in those cases, the separate results MUST be separately signed.

    The release workflow (.github/workflows/release.yml) is wired to sign every published release with Sigstore (keyless, GitHub OIDC → Fulcio → Rekor), emit an SLSA in-toto attestation, and carry npm provenance. SECURITY.md documents three independent verification paths: npm audit signatures, gh attestation verify, and cosign verify-blob-attestation. (Met after v1.0.0 is tagged.) URL: https://github.com/klodr/gmail-mcp/blob/main/SECURITY.md#verifying-releases-once-v1-is-out


    Enough for a badge!

    It is SUGGESTED that in the version control system, each important version tag (a tag that is part of a major release, minor release, or fixes publicly noted vulnerabilities) be cryptographically signed and verifiable as described in signed_releases. [version_tags_signed]

    The release workflow binds release signing to the GitHub OIDC identity of klodr/gmail-mcp. Git tags are cross-referenceable against the Rekor transparency log entry associated with each release. (Met after v1.0.0 is tagged.)


  • Other security issues


    Enough for a badge!

    The project results MUST check all inputs from potentially untrusted sources to ensure they are valid (an *allowlist*), and reject invalid inputs, if there are any restrictions on the data at all. [input_validation]
    Note that comparing input against a list of "bad formats" (aka a *denylist*) is normally not enough, because attackers can often work around a denylist. In particular, numbers are converted into internal formats and then checked if they are between their minimum and maximum (inclusive), and text strings are checked to ensure that they are valid text patterns (e.g., valid UTF-8, length, syntax, etc.). Some data may need to be "anything at all" (e.g., a file uploader), but these would typically be rare.

    Every tool input schema is defined with Zod (src/tools.ts). Strings use length caps and regex allowlists where applicable. Numbers have .max() bounds (maxResults ≤ 500, batchSize ≤ 100, messageIds.length ≤ 1000). File paths pass through the realpath-canonicalized jail allowlist (src/utl.ts). Email header values are stripped of \r, \n, \0 before assembly. URL: https://github.com/klodr/gmail-mcp/blob/main/src/tools.ts


    Enough for a badge!

    Hardening mechanisms SHOULD be used in the software produced by the project so that software defects are less likely to result in security vulnerabilities. [hardening]
    Hardening mechanisms may include HTTP headers like Content Security Policy (CSP), compiler flags to mitigate attacks (such as -fstack-protector), or compiler flags to eliminate undefined behavior. For our purposes least privilege is not considered a hardening mechanism (least privilege is important, but separate).

    ASSURANCE_CASE.md §4 "Common implementation weaknesses countered" documents hardening measure by CWE/OWASP slot — path-traversal jails, O_NOFOLLOW symlink defense, CRLF sanitisation, CSPRNG MIME boundary, TOCTOU re-realpath, Zod bounds, 0o600/0o700 file/dir modes, full SHA pinning of GitHub Actions. URL: https://github.com/klodr/gmail-mcp/blob/main/ASSURANCE_CASE.md


    Enough for a badge!

    The project MUST provide an assurance case that justifies why its security requirements are met. The assurance case MUST include: a description of the threat model, clear identification of trust boundaries, an argument that secure design principles have been applied, and an argument that common implementation security weaknesses have been countered. (URL required) [assurance_case]
    An assurance case is "a documented body of evidence that provides a convincing and valid argument that a specified set of critical claims regarding a system’s properties are adequately justified for a given application in a given environment" ("Software Assurance Using Structured Assurance Case Models", Thomas Rhodes et al, NIST Interagency Report 7608). Trust boundaries are boundaries where data or execution changes its level of trust, e.g., a server's boundaries in a typical web application. It's common to list secure design principles (such as Saltzer and Schroeer) and common implementation security weaknesses (such as the OWASP top 10 or CWE/SANS top 25), and show how each are countered. The BadgeApp assurance case may be a useful example. This is related to documentation_security, documentation_architecture, and implement_secure_design.

    ASSURANCE_CASE.md covers the full assurance argument — §1 threat model (actors, assets, 10 attack scenarios with mitigations), §2 trust boundaries (ASCII diagram of MCP client ↔ MCP server ↔ Gmail API with the local FS jail layout), §3 secure-design principles applied, §4 CWE/OWASP mitigation table with status per weakness. URL: https://github.com/klodr/gmail-mcp/blob/main/ASSURANCE_CASE.md


 Analysis 2/2 ●

  • Static code analysis


    Enough for a badge!

    The project MUST use at least one static analysis tool with rules or approaches to look for common vulnerabilities in the analyzed language or environment, if there is at least one FLOSS tool that can implement this criterion in the selected language. [static_analysis_common_vulnerabilities]
    Static analysis tools that are specifically designed to look for common vulnerabilities are more likely to find them. That said, using any static tools will typically help find some problems, so we are suggesting but not requiring this for the 'passing' level badge.

    CodeQL Advanced runs on every push and every PR, scanning both the javascript-typescript surface and the actions surface. Socket Security adds a second tool on the supply-chain axis. Scorecard runs weekly. URL: https://github.com/klodr/gmail-mcp/blob/main/.github/workflows/codeql.yml


  • Dynamic code analysis


    Enough for a badge!

    If the software produced by the project includes software written using a memory-unsafe language (e.g., C or C++), then at least one dynamic tool (e.g., a fuzzer or web application scanner) MUST be routinely used in combination with a mechanism to detect memory safety problems such as buffer overwrites. If the project does not produce software written in a memory-unsafe language, choose "not applicable" (N/A). [dynamic_analysis_unsafe]
    Examples of mechanisms to detect memory safety problems include Address Sanitizer (ASAN) (available in GCC and LLVM), Memory Sanitizer, and valgrind. Other potentially-used tools include thread sanitizer and undefined behavior sanitizer. Widespread assertions would also work.

    TypeScript transpiled to JavaScript runs on Node.js, a memory-safe runtime. There is no C/C++/Rust-with-unsafe code path in this project.



This data is available under the Community Data License Agreement – Permissive, Version 2.0 (CDLA-Permissive-2.0). This means that a Data Recipient may share the Data, with or without modifications, so long as the Data Recipient makes available the text of this agreement with the shared Data. Please credit Claude Perrin and the OpenSSF Best Practices badge contributors.

Project badge entry owned by: Claude Perrin.
Entry created on 2026-04-21 10:10:29 UTC, last updated on 2026-04-21 11:49:55 UTC. Last achieved passing badge on 2026-04-21 10:55:05 UTC.