RFC MCP Server

Instructions

Implementation Reference

• src/index.ts:197-244 (handler)

  The MCP tool handler for 'get_rfc' in the CallToolRequestSchema. Validates input, fetches RFC via service, formats output (full/metadata/sections), returns JSON text or error.

  case 'get_rfc': {
    if (typeof typedArgs.number !== 'string') {
      throw new McpError(
        ErrorCode.InvalidParams,
        'RFC number must be a string'
      );
    }
    
    try {
      const rfc = await rfcService.fetchRfc(typedArgs.number);
      
      // Format the output based on the requested format
      const format = typedArgs.format || 'full';
      let result;
      
      switch (format) {
        case 'metadata':
          result = rfc.metadata;
          break;
        case 'sections':
          result = rfc.sections;
          break;
        case 'full':
        default:
          result = rfc;
          break;
      }
      
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(result, null, 2),
          },
        ],
      };
    } catch (error) {
      return {
        content: [
          {
            type: 'text',
            text: `Error fetching RFC ${typedArgs.number}: ${error}`,
          },
        ],
        isError: true,
      };
    }
  }

• src/index.ts:126-146 (registration)

  Tool registration in ListToolsRequestSchema, defining name, description, and input schema for 'get_rfc'.

  {
    name: 'get_rfc',
    description: 'Fetch an RFC document by its number',
    inputSchema: {
      type: 'object',
      properties: {
        number: {
          type: 'string',
          description: 'RFC number (e.g. "2616")',
        },
        format: {
          type: 'string',
          description: 'Output format (full, metadata, sections)',
          enum: ['full', 'metadata', 'sections'],
          default: 'full',
        },
      },
      required: ['number'],
      additionalProperties: false,
    },
  },

• src/index.ts:129-144 (schema)

  Input schema definition for the 'get_rfc' tool, specifying parameters 'number' (required) and optional 'format'.

  inputSchema: {
    type: 'object',
    properties: {
      number: {
        type: 'string',
        description: 'RFC number (e.g. "2616")',
      },
      format: {
        type: 'string',
        description: 'Output format (full, metadata, sections)',
        enum: ['full', 'metadata', 'sections'],
        default: 'full',
      },
    },
    required: ['number'],
    additionalProperties: false,

• src/services/rfcService.ts:37-65 (helper)

  Core helper function fetchRfc that retrieves RFC content from IETF URLs (HTML preferred, TXT fallback), parses structure, caches result, returns RfcContent object.

  async fetchRfc(rfcNumber: string): Promise<RfcContent> {
    // Check cache first
    if (this.cache.has(rfcNumber)) {
      return this.cache.get(rfcNumber)!;
    }
  
    // Fetch the RFC in both HTML and TXT formats
    const txtUrl = `${this.baseUrl}/rfc${rfcNumber}.txt`;
    const htmlUrl = `${this.baseUrl}/rfc${rfcNumber}/`;
  
    try {
      // Try HTML first for better structure
      const htmlResponse = await axios.get(htmlUrl);
      const rfc = this.parseHtmlRfc(htmlResponse.data, rfcNumber, htmlUrl);
      this.cache.set(rfcNumber, rfc);
      return rfc;
    } catch (error) {
      try {
        // Fallback to TXT format
        console.error(`Failed to fetch HTML format for RFC ${rfcNumber}, trying TXT format`);
        const txtResponse = await axios.get(txtUrl);
        const rfc = this.parseTxtRfc(txtResponse.data, rfcNumber, txtUrl);
        this.cache.set(rfcNumber, rfc);
        return rfc;
      } catch (txtError) {
        throw new Error(`Failed to fetch RFC ${rfcNumber}: ${txtError}`);
      }
    }
  }