Rfcxml Mcp

A Model Context Protocol (MCP) server forstructured understandingof RFC documents.

Unlike existing text-based RFC MCP servers, this server leverages the semantic structure of RFCXML to enable:

- Normative requirements extraction(MUST/SHOULD/MAY) with structured output
- RFC dependency graphconstruction
- Definition scope management
- Implementation checklist generation

┌─────────────────────────┐ │ Markdown / PDF │ Display & Sharing ├─────────────────────────┤ │ Translation │ Explanation & Verification ├─────────────────────────┤ │ RFCXML MCP │ Common Understanding for AI & Humans ├─────────────────────────┤ │ RFCXML │ Single Source of Truth └─────────────────────────┘

Add the following to your MCP configuration file:

{ "mcpServers": { "rfcxml": { "command": "npx", "args": ["-y", "@shuji-bonji/rfcxml-mcp"] } } }

- Claude Desktop (macOS):~/Library/Application Support/Claude/claude_desktop_config.json
- Claude Desktop (Windows):%APPDATA%\Claude\claude_desktop_config.json
- Claude Code (project scope):.mcp.jsonat the project root
- Claude Code (user scope):~/.claude.json
- Claude Code (CLI):claude mcp add rfcxml -- npx -y @shuji-bonji/rfcxml-mcp

{ "mcpServers": { "rfcxml": { "command": "rfcxml-mcp" } } }

- get_rfc_structure- Get section hierarchy and metadata
- get_requirements- Extract normative requirements (MUST/SHOULD/MAY) with structure
- get_definitions- Get term definitions and their scope

- get_rfc_dependencies- Get referenced RFCs (normative/informative)
- get_related_sections- Get related sections within the same RFC

- validate_statement- Verify if a statement complies with RFC requirements
- generate_checklist- Generate implementation checklist

RFCs published after RFC 8650 (December 2019) are available in official RFCXML v3 format. Earlier RFCs may not have XML available.

This server includesautomatic fallbackfunctionality - when XML is unavailable, it parses the text format instead.

All responses include source information:

{ "rfc": 6455, "sections": [...], "_source": "text", "_sourceNote": "Warning: Parsed from text format. Accuracy may be limited." }

{ "metadata": { "title": "Transmission Control Protocol (TCP)", "docName": "draft-ietf-tcpm-rfc793bis-28", "number": 9293 }, "sections": [ { "number": "section-1", "title": "Purpose and Scope" }, { "number": "section-3", "title": "Functional Specification", "subsections": [ { "number": "section-3.1", "title": "Header Format" }, { "number": "section-3.5", "title": "Establishing a Connection", "subsections": [ { "number": "section-3.5.1", "title": "Half-Open Connections and Other Anomalies" }, { "number": "section-3.5.2", "title": "Reset Generation" } ] } ] } ], "referenceCount": { "normative": 15, "informative": 85 }, "_source": "xml" }

get_requirements- Extract Normative Requirements

{ "rfc": 9293, "filter": { "level": "MUST" }, "stats": { "total": 53, "byLevel": { "MUST": 53 } }, "requirements": [ { "id": "R-section-3.5-5", "level": "MUST", "text": "A TCP implementation support simultaneous open attempts (MUST-10).", "section": "section-3.5", "sectionTitle": "Establishing a Connection" }, { "id": "R-section-3.7.1-9", "level": "MUST", "text": "TCP endpoints implement both sending and receiving the MSS Option (MUST-14).", "section": "section-3.7.1", "sectionTitle": "Maximum Segment Size Option" } ], "_source": "xml" }

get_rfc_dependencies- Get RFC Dependencies

{ "rfc": 9293, "normative": [ { "rfcNumber": 791, "title": "Internet Protocol", "anchor": "RFC0791" }, { "rfcNumber": 2119, "title": "Key words for use in RFCs to Indicate Requirement Levels" }, { "rfcNumber": 5681, "title": "TCP Congestion Control" } ], "informative": [ { "rfcNumber": 793, "title": "Transmission Control Protocol" }, { "rfcNumber": 1122, "title": "Requirements for Internet Hosts - Communication Layers" } ], "_source": "xml" }

generate_checklist- Generate Implementation Checklist

# RFC 9293 Implementation Checklist Transmission Control Protocol (TCP) Role: Client ## Required (MUST / REQUIRED / SHALL) - [ ] A TCP implementation support simultaneous open attempts (MUST-10). (section-3.5) - [ ] TCP endpoints implement both sending and receiving the MSS Option (MUST-14). (section-3.7.1) - [ ] The RTO be computed according to the algorithm in, including Karn's algorithm (MUST-18). (section-3.8.1) ## Optional (MAY / OPTIONAL) - [ ] Implementers include "keep-alives" in their TCP implementations (MAY-5). (section-3.8.4)

{ "metadata": { "title": "The WebSocket Protocol", "number": 6455 }, "sections": [ { "number": "1", "title": "Introduction" }, { "number": "5", "title": "Data Framing" } ], "_source": "text", "_sourceNote": "Warning: Parsed from text format. Accuracy may be limited." }

See theexamples/directory for complete checklist samples:

Generate an implementation checklist for RFC 9293 (TCP).

src/ ├── index.ts # MCP server entry point ├── config.ts # Centralized configuration ├── constants.ts # BCP 14 keyword definitions + RFC number limits ├── services/ │ ├── rfc-fetcher.ts # RFC fetching (parallel) │ ├── rfc-service.ts # RFC parse & cache management │ ├── rfcxml-parser.ts # RFCXML parser │ ├── rfc-text-parser.ts # Text fallback parser │ └── checklist-generator.ts # Checklist generation service ├── tools/ │ ├── definitions.ts # MCP tool definitions │ └── handlers.ts # Tool handlers (toolHandlers map) ├── types/ │ └── index.ts # Type definitions └── utils/ ├── cache.ts # LRU cache ├── fetch.ts # Parallel fetch utility ├── logger.ts # Logger abstraction ├── requirement-extractor.ts # Shared requirement extraction ├── section.ts # Section search utilities ├── statement-matcher.ts # Weighted statement matching ├── text.ts # Text processing utility └── validation.ts # Input validation

┌─────────────────┐ │ fetchRFCXML() │ └────────┬────────┘ │ Parallel requests ┌────┴────┬────────────┐ ▼ ▼ ▼ ┌────────┐ ┌────────┐ ┌────────┐ │RFC │ │IETF │ │Data- │ │Editor │ │Tools │ │tracker │ └────┬───┘ └────┬───┘ └────┬───┘ │ │ │ └────┬─────┴──────────┘ │ Promise.any (first success) ▼ ┌───────────┐ │ Successful│ → Cancel other requests via AbortController │ Response │ └───────────┘

# Install dependencies npm install # Development mode npm run dev # Build npm run build # Test (watch mode) npm test # Test (single run — for CI etc.) npm test -- --run # E2E test (MCP client integration) npm run test:e2e # Lint npm run lint # Format npm run format

- mjpitz/mcp-rfc- Text-based RFC MCP
- ietf-tools/RFCXML- RFCXML schema
- xml2rfc- IETF official tool

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