US Federal Regulations (CFR) in VS Code

Questions it answers

Read a CFR or eCFR section, or search US federal regulations and the Federal Register. Ask "what does 21 CFR 11.10 say?", "which regulations mention respirator fit testing?" or "what has the FDA proposed on food dyes this year?".

US Federal Regulations reads two official United States sources directly: the Electronic Code of Federal Regulations (eCFR) for the current text of any section of the Code of Federal Regulations, and the Federal Register for the rules, proposed rules, notices and presidential documents the agencies publish each day. People also call it Rules Lookup.

Use it for regulatory compliance questions about FDA, OSHA, EPA, SEC, FTC or FAA rules when the text is in the CFR or the Federal Register. It does not cover state law, court decisions or other countries.

A section lookup returns the citation, heading, full text, statutory authority and amendment history of the section, with the date the eCFR is up to date as of and a link to the section. A very long section is cut and says so. A search returns the matching sections or documents with the agency, the publication date, the comment deadline and effective date where there is one, and the CFR parts a document changes.

This is general information, not legal advice. The eCFR is an unofficial edition kept up to date by the Office of the Federal Register; the legal text is the Federal Register and the annual CFR. A rule applies differently to each situation, so check the current official text and ask a qualified lawyer before you rely on it.

It covers United States federal regulations only: not state or local law, court decisions, statutes, other countries' rules or guidance documents that are not in the Federal Register.

It stores nothing about you: answers are cached for up to six hours (sections) or an hour (searches), and the only lasting record is a daily count of calls per tool.

What it can do

• Reads the current text of any section of the US Code of Federal Regulations (eCFR)
• Shows a section's heading, statutory authority and amendment history with a link
• Searches eCFR text and federal compliance rules by words, in one title or all of them
• Searches the Federal Register for rules, proposed rules, notices, rulemakings and executive orders
• Shows comment deadlines, effective dates and the CFR parts a document changes

Tools

• get_cfr_section, Read an eCFR section (FDA, OSHA, EPA). Use this when the user asks what a specific US federal regulation says, including an FDA, OSHA, EPA, SEC, FTC or FAA section of the eCFR, for example "what does 21 CFR 11.10 say?", "read 29 CFR 1910.134" or "show me 17 CFR 240.10b-5". Pass the CFR title number and the section number. Returns the current text, heading, statutory authority and amendment history of the section, the date the eCFR is up to date as of and a link to it. A very long section is cut at a paragraph and flagged with nextOffset; call again with that offset to read on. This is general information, not legal advice. Do not use it to find a regulation by topic (use search_cfr), for statutes, state law or court decisions, or to decide whether someone complies.
• search_cfr, Search federal regulations and compliance. Use this when the user asks which US federal regulations or compliance rules cover a topic, including an OSHA, EPA or FDA rule, for example "which regulations mention respirator fit testing?", "find the rules on electronic signatures in title 21" or "where does the CFR define small business?". Pass 2 to 4 words to find and, if known, the CFR title to search in. A section must hold every word; when nothing does, the search drops the last words and says which query matched (matchedQuery). Returns the best matching sections with citation, heading, an excerpt, the agency and a link; use get_cfr_section to read one in full. This is general information, not legal advice. Do not use it for recent rulemaking news (use search_federal_register), statutes, state law or court decisions.
• search_federal_register, Search the Federal Register and rulemakings. Use this when the user asks what federal agencies have published, proposed or announced, including a rulemaking, for example "what has the FDA proposed on food dyes?", "find final rules on noncompete agreements" or "which executive orders mention AI this year?". Pass the words to find and optionally the document type (rule, proposed_rule, notice, presidential_document) and a publication date range. Returns each document's title, type, agencies, publication date, abstract, effective date, comment deadline, the CFR parts it changes and a link. This is general information, not legal advice. Do not use it to read the current text of a regulation (use get_cfr_section), or for state law, bills, court decisions or non-US rules.

Add US Federal Regulations (CFR) in VS Code

VS Code reads MCP servers from mcp.json and offers their tools to Copilot Chat in Agent mode. A workspace file at .vscode/mcp.json applies to that project. For every workspace, run MCP: Open User Configuration from the Command Palette and add the same entry there. These steps were checked against the VS Code MCP servers guide on 2026-10-09.

Create or edit the file so it contains this server. VS Code uses a top-level servers object, not mcpServers. Merge it with servers you already have.

{
  "servers": {
    "rules": {
      "type": "http",
      "url": "https://rules.openkrill.app/mcp"
    }
  }
}

No command, no headers and no input variables for a key: US Federal Regulations (CFR) answers without a login. Save the file and select Start above the entry. VS Code asks once whether you trust the server: confirm it. Run MCP: List Servers to check that US Federal Regulations (CFR) is running. You should see get_cfr_section, search_cfr, search_federal_register.

Open the Chat view, choose Agent mode and ask: What does 21 CFR 11.10 say about electronic records controls? The Configure Tools button in the chat input lists the tools of each server, and VS Code may ask you to confirm the first call. The server is public and read-only. It sees only the arguments of each call, so do not paste secrets into the question.

Command line users can add it to the user profile in one step with code --add-mcp and the same name, type and url as JSON. The portable .mcp.json at the project root also works in VS Code, with mcpServers as its top-level key. An organization can turn MCP off through Copilot policy: if the MCP commands are missing, ask the admin.

If it does not work

A call checked on 2026-10-17

21 CFR 11.10 is the electronic-records section named in the plugin's starter prompts. The request below was posted to https://rules.openkrill.app/mcp as tools/call. HTTP 200. Source: the US Federal Regulations (CFR) server, read 2026-10-17.

{
  "method": "tools/call",
  "params": {
    "name": "get_cfr_section",
    "arguments": {
      "title": 21,
      "section": "11.10"
    }
  }
}

• asOf. 2026-10-15
• source. Electronic Code of Federal Regulations (eCFR, ecfr.gov), Office of the Federal Register
• heading. Controls for closed systems.
• citation. 21 CFR 11.10
• notice. The eCFR is an unofficial, continuously updated edition of the Code of Federal Regulations. The legal text is the Federal Register and the annual CFR on govinfo.gov. This is general information, not legal advice. Regulat
• url. https://www.ecfr.gov/current/title-21/section-11.10

Repeat the call yourself if you need a newer reading. Cached answers expire. A rate limit is not a result: wait and try again. Nothing in the call is a ranking, a filing, or advice.

Using it in production

Nothing to install and nothing to run: no package, no Python or Node.js version and no environment variable. US Federal Regulations (CFR) runs on our servers, and your client only needs the URL https://rules.openkrill.app/mcp.

Use it in other apps

• US Federal Regulations (CFR) in ChatGPT
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• US Federal Regulations (CFR) in Pi

Roles that use US Federal Regulations (CFR)

• Compliance reader guide

Frequently asked questions

Words on this page

• MCP (Model Context Protocol) definition
• Streamable HTTP transport definition
• Tool primitive definition
• Rate limit policy definition

Source: plugin listing for rules in this repository, and a live tools/call on 2026-10-17. As of 2026-10-17.