fedregister

The Federal Register is where the United States government publishes what it is about to do and what it has done: final rules, proposed rules open for public comment, notices, and presidential documents. fedregister wraps the Register's public API v1 in a small CLI and a stdio MCP server, so a person — or an agent — can search that record, watch comment deadlines, and pull the history of a rulemaking without scraping web pages. The API is public and keyless; no account or token is needed.

What the eight tools do:

• search_documents — search everything published since

  1994. Flat arguments (term, document types, agencies, docket id, regulation id number, CFR title/part, sections, topics, significance, publication and effective date bounds, paging, ordering, field selection) are translated into the API's conditions[...] query parameters.

• get_document — fetch one document by its document number.

• get_documents_batch — fetch up to 20 documents in a single call.

• get_facet_counts — counts of matching documents grouped by a facet: a document field such as type, agency, or topic, or a time bucket from daily through yearly.

• get_public_inspection — search the pre-publication filings currently on public inspection, including the available_on date and the special_filing flag.

• list_agencies — every agency that publishes in the Register.

• open_comment_periods — a labelled composition: it pages through recent documents (a scan window reaching 120 days back, at most 5 pages of 1000), keeps the ones whose comment period is still open, and returns them sorted by deadline as {results, complete, truncated}, where complete says whether the whole scan window was read and truncated whether the limit (default 50) cut the list.

• far_case_history — a labelled composition: the full document history of a FAR/DFARS case, searched by case number in chronological order, from the proposed rule through the final rule.

Two behaviours are worth knowing about:

• Client-side comment-date filters (labelled). The API publishes no comment-date search condition, so search_documents' optional comment_date_gte / comment_date_lte arguments are applied locally, after the response arrives: documents whose comments_close_on is null or outside the range are dropped from the returned page, and the rest of the response envelope is returned unchanged. Every other search result is the upstream JSON verbatim.

• Pacing. Requests are polite by design: at least 300 ms pass between request starts, and if the API answers HTTP 429 the client waits the Retry-After interval (60 seconds by default) and retries the same request once before reporting an error.

The API base URL defaults to https://www.federalregister.gov/api/v1 and can be overridden with the FEDERAL_REGISTER_API_BASE environment variable.

CLI

Each tool is a subcommand taking one JSON argument string (list_agencies takes none):

npx @reneturcios/fedregister search_documents '{"term":"endangered species","type":["PRORULE"],"comment_date_gte":"2026-11-01"}'
npx @reneturcios/fedregister get_document '{"document_number":"2026-12345"}'
npx @reneturcios/fedregister get_documents_batch '{"document_numbers":["2026-12345","2026-12346"]}'
npx @reneturcios/fedregister get_facet_counts '{"facet":"monthly","term":"climate"}'
npx @reneturcios/fedregister get_public_inspection '{"special_filing":true}'
npx @reneturcios/fedregister list_agencies
npx @reneturcios/fedregister open_comment_periods '{"limit":10}'
npx @reneturcios/fedregister far_case_history '{"case_number":"FAR Case 2023-008"}'
npx @reneturcios/fedregister --version

Output is the tool's result text (the upstream JSON, or a composition's JSON). Exit codes: 0 on success, 1 on a runtime error (including a validation or upstream failure), 2 on a usage error.

Related MCP server: regulationsgov-mcp

MCP server

npx -y @reneturcios/fedregister mcp

MCP client config:

{
  "mcpServers": {
    "fedregister": {
      "command": "npx",
      "args": ["-y", "@reneturcios/fedregister", "mcp"]
    }
  }
}

Docker

docker run -i ghcr.io/cloudcorprecords/fedregister
docker run --rm ghcr.io/cloudcorprecords/fedregister list_agencies

Development

npm install
npm run build   # tsc -> dist/
npm test        # tsx --test test/*.test.ts (fake fetch + fake clock + fake sleep, no network)
npm run dev     # run the CLI from source

License

MIT — Copyright (c) 2026 Rene Turcios