Search the Federal Register — the daily journal of US proposed rules, final rules, notices, and presidential documents (1994–present) — filtering by full-text query, document type, agency slug, publication date range, and whether the rule is open for comment. The primary discovery entry point: results carry the document number (open with regulations_get_document), docket IDs, RINs, and affected CFR parts that chain into the comment and codified-text tools. The Federal Register caps navigation at 50 pages and the match count at 10,000; when a result set is larger, narrow with published_after/published_before rather than paging deeper.
Fetch one Federal Register document by its FR document number — full metadata (title, type, agencies, abstract, action, effective/comment dates, RINs) plus the cross-source handles that make this a workflow server. The output carries the docket ID (chain into regulations_get_docket or regulations_find_comments) and the affected CFR parts (chain into regulations_get_cfr_section). Set include_full_text only when the rule body itself is needed — final rules can run tens of thousands of words.
Explore the codified Code of Federal Regulations via eCFR in two modes. "structure" walks the CFR hierarchy (all 50 titles, or one title's chapters → parts → sections) to discover a cite when the exact citation is unknown. "search" runs a full-text query across the codified CFR and returns matching sections with their hierarchy path and a snippet. Both modes feed regulations_get_cfr_section. The source (mirror or live) is reported on each search result.
Read the codified text of a specific CFR section (or a whole part) via eCFR — current or as of a past date. Answers "what does 40 CFR 50.1 say today?" and "...as of 2019-01-01?". Provide title + part + section for one section, or omit section to fetch the whole part (large parts can be very long; prefer a specific section when you know it). eCFR retains historical versions back to roughly 2017; a date before coverage is rejected with guidance. Current single-section reads are served from a synced local mirror when available; the source is reported.
Pull a rulemaking docket from Regulations.gov by docket ID (e.g. "EPA-HQ-OAR-2025-0194") — the docket's metadata (title, agency, RIN, abstract) and the documents filed in it (NPRM, final rule, supporting materials). The docket is the folder holding a rule's whole paper trail; each returned document's objectId feeds regulations_find_comments. A docket often contains hundreds of supporting materials — filter document_types to "Proposed Rule"/"Rule" to find the rule documents themselves. Requires REGULATIONS_GOV_API_KEY (free at https://api.data.gov/signup/); the Federal Register and eCFR tools work without it.