{
  "markdown": "# cfr-mcp\n\n[![CI](https://github.com/mccallar/cfr-mcp/actions/workflows/ci.yml/badge.svg)](https://github.com/mccallar/cfr-mcp/actions/workflows/ci.yml)\n[![PyPI](https://img.shields.io/pypi/v/cfr-mcp)](https://pypi.org/project/cfr-mcp/)\n\nAn MCP server that gives AI assistants access to the **US Code of Federal Regulations**.\n\nAsk \"what does 21 CFR 101.9 require?\" or \"has 40 CFR 261 changed since 2023?\" and get\nthe actual regulation text, with citations, instead of a plausible-sounding guess.\n\nUnofficial community project. Not affiliated with or endorsed by the Office of the\nFederal Register, NARA, or GPO, and uses no government seals or logos.\n\nMaintained by one person as a personal project and provided as-is (MIT). Issues and\npull requests are welcome but may not get a quick response. To report a security\nissue, see [SECURITY.md](SECURITY.md).\n\n<!-- mcp-name: io.github.mccallar/cfr-mcp -->\n\n## Install\n\nRequires Python 3.11+. No API key — the eCFR and Federal Register APIs are open.\n\nClaude Code:\n\n```bash\nclaude mcp add cfr -- uvx cfr-mcp\n```\n\nAny other MCP client:\n\n```json\n{\n  \"mcpServers\": {\n    \"cfr\": {\n      \"command\": \"uvx\",\n      \"args\": [\"cfr-mcp\"]\n    }\n  }\n}\n```\n\n## Tools\n\n| Tool | What it does |\n|---|---|\n| `lookup_citation` | Text of a citation — `21 CFR 101.9`, `40 CFR 261.4(b)(1)`, `40 CFR Part 261 Subpart C` |\n| `search_regulations` | Full-text search; returns citations and snippets, never bodies |\n| `where_does_term_appear` | Which titles contain a term, with hit counts. Fetches no text |\n| `browse_structure` | The hierarchy of a title or part, no text |\n| `what_changed` | Amendment history for a citation, linking each change to the Federal Register rule that caused it, plus published corrections |\n| `compare_versions` | Diff of a citation's text between two dates — see exactly what an amendment changed |\n| `list_agencies` | Maps agency names to the CFR titles they administer |\n\nPoint-in-time works throughout: pass `date` as `YYYY-MM-DD` to read the CFR as it stood.\n\n## Design notes\n\n**Context budget is the whole game.** The eCFR `full` endpoint returns an entire\ndownloadable XML document for a title-level request. Every tool here caps output and\ndegrades to an outline rather than dumping text into the model's context. Title-level\nXML requests are refused outright.\n\n**Dates must be resolved, not assumed.** Versioner routes 404 on dates that aren't\nvalid issue dates for a title, so the client resolves through `titles.json` first\nrather than passing today's date blindly.\n\n**Caching is courtesy.** The eCFR publishes no rate limit and has no key to identify\ncallers politely, so the client caches to disk (historical dates forever, since\npoint-in-time content is immutable) and self-limits concurrency. The cache lives in\n`~/.cache/cfr-mcp` (respects `XDG_CACHE_HOME`); set `CFR_MCP_CACHE_DIR` to relocate it.\n\n## Legal\n\nRegulation text is free to reproduce. **1 CFR 2.6** states that any person may reproduce\nor republish material appearing in the Federal Register, with no restrictions on what is\nreproduced, who reproduces it, or where. Federal government works are also outside\ncopyright under 17 U.S.C. §105.\n\n**Incorporation by reference.** Some CFR sections incorporate private standards\n(ASTM, NFPA, ASHRAE) whose copyright status after incorporation remains unsettled.\nThe eCFR does not contain the text of those standards and neither does this server —\nit returns the citation only. Obtain standards from the issuing organization or the\nOffice of the Federal Register reading room.\n\n**Status of the text.** The eCFR is authoritative but unofficial. Anyone relying on it\nfor legal research should verify against the current official CFR, the daily Federal\nRegister, and the List of CFR Sections Affected (LSA).\n\n**Not legal advice.** This is a retrieval tool. It returns the text of regulations; it\ndoes not tell you whether you are compliant with them.\n\n## Development\n\n```bash\nuv sync --extra dev\nuv run pytest\n```\n\nMIT licensed.\n",
  "bytes": 3998,
  "sha": "4b1eefeaddba3228605c1cfbc1ee705b37741e0ebb306b7d56fe2530c4b1bb5d",
  "repo_slug": "mccallar/cfr-mcp",
  "fonte": "repo",
  "truncated": false,
  "api": "https://agentalog.com/api/listings/mcp_io_github_mccallar_cfr_mcp_57d61f8a/readme"
}