US Code of Federal Regulations
PYPI · CFR-MCP
Look up, search, and track changes to the US Code of Federal Regulations (eCFR).
Available components
Last scanned (7 hours ago)
Scores higher than 64% of PyPI servers
Category Education and Research
How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. How we score → Why this is hard to score →
Supply Chain Security50
- Malware scan not yet available for this package.Unverified
- No known CVEs affecting this package version or its production dependencies.Pass
- Runs hatchling.build at install time, a recognised build step with no custom scripting around it. View diagnostics → Pass
- 1 of 32 dependencies flagged as unhealthy. View diagnostics → Partial
Provenance & Transparency48
- Source repository is publicly reachable at the declared URL. View diagnostics → Pass
- Provenance check failed: no build-provenance attestation is published. See how to fix → View diagnostics → Fail
- Clear OSI-approved license (MIT).Pass
- Actively maintained (last published 67 days ago).Pass
- Publishes a security disclosure policy (SECURITY.md).Pass
Schema Quality & AI Usability71
- AI-judged instruction clarity (good).Pass
- Tool/resource definitions use about 595 tokens (~85/item across 7 items; 7 tools + 0 resources), lean.Pass
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage83
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 40% of tool parameters carry a description.Partial
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 7 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 8 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 5 Nov 26 −15
- Malware scan: pass → unverified ▼ security
- 1 Nov 26 0
- Stability: 0.97 → pass security
- 31 Oct 26 0
- Provenance: unverified → fail ▼ security
- Stability: pass → 0.97 functional
- 30 Oct 26 0
- Provenance: fail → unverified ▼ security
- 25 Oct 26 0
- Stability: 0.97 → pass security
- 24 Oct 26 0
- Provenance: unverified → fail ▼ security
- Stability: pass → 0.97 functional
- 23 Oct 26 0
- Provenance: fail → unverified ▼ security
- 18 Oct 26 0
- Stability: 0.97 → pass security
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 5 Nov 2026 · Analysed pypi/cfr-mcp@0.2.2
Provenance No attestation
The registry publishes no build provenance for this version, so there is nothing to verify.
| Result | No attestation |
|---|---|
| Ecosystem | pypi |
| Reason | No attestation published |
Background: How many MCP packages publish verified provenance →
Install scripts 1 script
| Hook | Tier | Command |
|---|---|---|
| build_backend | allowlisted | hatchling.build |
Background: Why install scripts are a supply-chain risk →
Dependencies 32 packages
| Packages resolved | 32 |
|---|---|
| No linked repository | 1 |
| Tree resolution | Complete |
Background: SBOMs and build attestations, explained →
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
browse_structure ~41
Return the CFR hierarchy for a title (or one part) without any text.
| Name | Type | Req | Description |
|---|---|---|---|
| date | – | – | – |
| part | – | – | – |
| title | integer | yes | – |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
compare_versions ~148
Show how a citation's text differs between two dates, as a diff. Use what_changed first to find amendment dates worth comparing; pass the day before an amendment as date_a and the amendment date as date_b to see exactly what that rule changed. Both dates must be 2017-01-03 or later.
| Name | Type | Req | Description |
|---|---|---|---|
| citation | string | yes | A section citation like '40 CFR 261.4', optionally with a paragraph: '40 CFR 261.4(b)' |
| date_a | string | yes | Earlier date, YYYY-MM-DD |
| date_b | – | – | Later date, YYYY-MM-DD. Omit for the current text. |
| max_chars | integer | – | – |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
list_agencies ~45
List federal agencies and the CFR titles/chapters they administer. Use this to turn a name like "EPA" into the right CFR title before searching.
| Name | Type | Req | Description |
|---|---|---|---|
| filter | – | – | – |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
lookup_citation ~106
Retrieve the text of a specific CFR citation. Large parts return an outline of their sections instead of full text; follow up with a specific section citation to read it.
| Name | Type | Req | Description |
|---|---|---|---|
| citation | string | yes | e.g. '21 CFR 101.9', '40 CFR 261.4(b)(1)', '40 CFR Part 261 Subpart C' |
| date | – | – | YYYY-MM-DD for point-in-time text. Omit for current. |
| max_chars | integer | – | – |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
search_regulations ~79
Full-text search across the CFR. Returns citations, headings and short snippets only — never full text. Follow up with lookup_citation to read anything.
| Name | Type | Req | Description |
|---|---|---|---|
| agency | – | – | Agency slug from list_agencies |
| date | – | – | – |
| limit | integer | – | – |
| query | string | yes | – |
| title | – | – | Limit to a CFR title |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
what_changed ~77
List amendment dates for a citation, plus any published corrections. Each amendment is cross-linked to the Federal Register rule that caused it, with a URL to the rulemaking (whose preamble explains the why). Follow up with compare_versions to see exactly what text changed.
| Name | Type | Req | Description |
|---|---|---|---|
| citation | string | yes | – |
| since | – | – | YYYY-MM-DD |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
where_does_term_appear ~71
Show which titles/chapters/parts contain a term, with hit counts. Cheap orientation tool: fetches no regulation text at all. Use this before searching when you don't know which part of the CFR governs a topic.
| Name | Type | Req | Description |
|---|---|---|---|
| date | – | – | – |
| query | string | yes | – |
| Name | Type | Req | Description |
|---|---|---|---|
| result | string | yes | – |
No examples provided.
How do I install the US Code of Federal Regulations MCP server?
US Code of Federal Regulations runs locally as a PyPI package, launched with uvx cfr-mcp. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
pypi · cfr-mcp
claude mcp add mccallar-cfr-mcp -- uvx cfr-mcp
What is the US Code of Federal Regulations MCP server?
US Code of Federal Regulations is an MCP server listed in the public MCP registry as io.github.mccallar/cfr-mcp. Look up, search, and track changes to the US Code of Federal Regulations (eCFR). This page covers its PyPI package (cfr-mcp).
Is the US Code of Federal Regulations MCP server safe to use?
US Code of Federal Regulations scores 68 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 5 November 2026. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the US Code of Federal Regulations MCP server expose?
US Code of Federal Regulations exposes 7 tools: lookup_citation, search_regulations, where_does_term_appear, browse_structure, what_changed, and 2 more. Their descriptions and schemas cost roughly 567 tokens of context every time the server is loaded.
Is the US Code of Federal Regulations MCP server still maintained?
US Code of Federal Regulations is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.
What licence is the US Code of Federal Regulations MCP server under?
US Code of Federal Regulations declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.