eCFR MCP

eCFR MCP

A Model Context Protocol server that wraps the eCFR (Electronic Code of Federal Regulations) API as deterministic tool calls. Built for federal contracting officers, attorneys, compliance teams, regulatory affairs analysts, and anyone who needs current or historical text from the FAR, DFARS, agency FAR supplements, or any other CFR title.

13 tools covering full CFR text and structure. Hardened across multiple live audit rounds. MIT licensed. No API key required.

What it does

Current Regulatory Text

• get_cfr_content: full current text of any CFR title, chapter, subchapter, part, subpart, or section
• get_cfr_structure: table of contents / hierarchical structure for any CFR part
• get_ancestry: ancestry path from a section back up to the title (useful for citation building)
• list_sections_in_part: enumerate every section in a part with titles
• Coverage includes FAR (48 CFR Chapter 1), DFARS (48 CFR Chapter 2), and all agency FAR supplements (NFS, AFFARS, AFARS, NMCARS, DARS, DOSAR, HHSAR, EPAAR, IAAR, etc.)

Search

• search_cfr: full-text search across the entire CFR
• Filter by title, agency, date range
• Hierarchical search within a specific part or subpart

Version History and Comparison

• get_version_history: full version history for any section showing every amendment
• compare_versions: side-by-side comparison of two versions of a section
• find_recent_changes: list sections amended after a given date
• Returns effective dates and Federal Register references for every change

Point-in-Time Lookups

• get_cfr_content with historical date parameter: text of a section as it stood on a specific date
• Trace evolution of a clause over time
• Critical for legacy contract administration where the original FAR clause text governs

FAR-Specific Tools

• lookup_far_clause: pull a specific FAR clause (e.g. 52.212-4, 52.219-14)
• find_far_definition: search FAR Part 2 definitions
• Provision/clause matrices and applicability

Corrections

• get_corrections: recent corrections published in the Federal Register
• Identify regulations with pending or recent corrections

Agency Lookups

• list_agencies: every agency with regulations in the CFR
• get_latest_date: most recent eCFR update timestamp

Use cases

• Look up exact FAR clause text for a contract file or contract write-up
• Build defensible compliance memos that cite current and prior CFR text
• Track when a FAR/DFARS section was amended and what it said before
• Compare current FAR text to what was in force at award (for protest defense or contract interpretation disputes)
• Find every CFR section affected by a specific Federal Register rule
• Pull definitions from FAR 2.101 and DFARS 202.101 with surrounding context

Compatibility

• Claude Desktop (one-click .mcpb install or Copy JSON)
• Codex (ChatGPT) via TOML config or codex mcp add
• Gemini CLI via ~/.gemini/settings.json
• Copilot via .vscode/mcp.json in VS Code
• Claude Code, Cursor, Cline, Zed, Continue, and any other MCP-compatible client

Install

No API key required.

{
  "mcpServers": {
    "ecfr": {
      "command": "uvx",
      "args": ["--refresh-package", "ecfr-mcp", "--from", "ecfr-mcp", "ecfr-mcp"]
    }
  }
}

TOML config (Codex):

[mcp_servers.ecfr]
command = "uvx"
args = ["--refresh-package", "ecfr-mcp", "--from", "ecfr-mcp", "ecfr-mcp"]

PyPI: pip install ecfr-mcp or uvx ecfr-mcp

Example prompts

• "Read me the current text of FAR 52.212-4."
• "What did FAR 15.404-4 say on January 1, 2022 vs today?"
• "Pull the full version history for FAR 19.808-1 since 2015."
• "Find the FAR definition of 'commercial product'."
• "Show me every section in DFARS subpart 252.227 with their titles."
• "Search the CFR for the phrase 'cybersecurity maturity model certification'."
• "What FAR sections were amended in the last 90 days?"
• "Compare the current text of FAR 16.601 to what it said on January 1, 2020."
• "Pull the ancestry path for DFARS 252.204-7012 (which subpart, part, chapter, title)."

Hardening

Live-audited against the production eCFR API across multiple rounds. Handles XML parsing for full-text sections (FAR 2.101 alone is ~109KB), historical date resolution, version diff calculation, and pagination for large search results. Pydantic models use extra="forbid" to surface schema drift. Tested across the full FAR/DFARS/agency-supplement hierarchy.

Source

• GitHub: https://github.com/1102tools/federal-contracting-mcps/tree/main/servers/ecfr-mcp
• PyPI: https://pypi.org/project/ecfr-mcp/
• Docs: https://1102tools.com/install
• Part of the 1102tools suite: 8 federal contracting MCPs + 6 Claude Skills
• License: MIT