MCP server

eCFR.io Federal Regulations Official

io.ecfr/ecfr

Checked 26 Oct 2026, 08:29 UTC · Connected to it and listed its tools

Search and read US federal regulations with legal and inline citations linking to ecfr.io.

Website Source

At a glance

Type

MCP server

Publisher

ecfr.io (verified by the MCP Registry)

Status

Working at last check

Tools

3

Token cost

About 642 tokens per request

Sets up in

Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok

Last checked

26 Oct 2026, 08:29 UTC

Connect it to your agent

Add to CursorAdd to VS CodeVS Code Insiders

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

claude mcp add --transport http ecfr https://ecfr.io/mcp

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

[mcp_servers.ecfr]
url = "https://ecfr.io/mcp"

Gemini CLI

{"mcpServers":{"ecfr":{"httpUrl":"https://ecfr.io/mcp"}}}

Cursor

{"mcpServers":{"ecfr":{"url":"https://ecfr.io/mcp"}}}

VS Code

{"servers":{"ecfr":{"type":"http","url":"https://ecfr.io/mcp"}}}

Antigravity

agy mcp add ecfr https://ecfr.io/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"ecfr","server_url":"https://ecfr.io/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"ecfr","server_url":"https://ecfr.io/mcp"}

Tools

• get_regulation ~306 tokens
  Retrieve regulation text and child links by canonical path returned by search, e.g. /Title-31/Section-10.1. Inspect dates and stale flags. Follow nextOffset until null for all text. For every regulatory claim or quotation, include the returned inlineCitation (Markdown link to ecfr.io), or legalCitat
• list_titles ~70 tokens
  List the CFR titles with source dates and canonical ecfr.io URLs. Browse children with get_regulation.
• search_regulations ~266 tokens
  Search current US CFR text or a citation such as 31 CFR 10.1. Returns snippets and legal/inline citations with ecfr.io links. Fetch matching regulations before quoting. For every regulatory claim or quotation, include the returned inlineCitation (Markdown link to ecfr.io), or legalCitation including

Browse

• Converting to Markdown
• Legal research

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