Congress.gov API MCP Server

Congress.gov API MCP Server

This is a Model Context Protocol (MCP) server designed to provide access to the official Congress.gov API (v3) using a hybrid approach:

• MCP Resources: For direct lookups of core legislative entities (Bills, Members, Congresses, Committees, general Info) using standardized URIs.
• MCP Tools: For more complex operations like searching across collections (congress_search) and retrieving related data lists (congress_getSubResource).

This server acts as a bridge, allowing MCP clients (like AI assistants or development tools) to easily query and utilize U.S. legislative data.

Project Structure

• /src: Contains all source code.
  • /config: Configuration management (ConfigurationManager.ts).
  • /services: Core logic for interacting with Congress.gov API (CongressApiService.ts, RateLimitService.ts).
  • /tools: MCP tool definitions (search/, subresource/, index.ts).
  • /types: TypeScript interfaces and Zod schemas.
  • /utils: Shared utility functions (logging, errors, etc.).
  • resourceHandlers.ts: Logic for handling core entity resource requests.
  • createServer.ts: Server instance creation, resource and tool registration.
  • server.ts: Main application entry point.
• /dist: Compiled JavaScript output (generated by npm run build).
• /docs: Project documentation (PRD, Feature Spec, RFCs).
• package.json: Project metadata and dependencies.
• tsconfig.json: TypeScript compiler options.
• .eslintrc.json, .prettierrc.json: Linting and formatting rules.
• .env: (Not committed) For storing CONGRESS_GOV_API_KEY.

Getting Started

1. Install Dependencies:

   npm install
   

2. Set API Key: Create a .env file in the project root and add your Congress.gov API key:

   CONGRESS_GOV_API_KEY=YOUR_API_KEY_HERE
   

   (Get a key from https://api.data.gov/signup/)

3. Build the Server:

   npm run build
   

4. Run the Server:

   npm start
   

   (This runs node dist/server.js)

Alternatively, run in development mode using npm run dev (uses ts-node and nodemon).

Usage with MCP Client

Connect your MCP client to the running server (e.g., via stdio if running locally).

Accessing Resources

Use the access_mcp_resource command/method with the appropriate URI.

Examples:

• Get Bill H.R. 3076 (117th Congress):

  <access_mcp_resource>
  <server_name>congress-server</server_name>
  <uri>congress-gov://bill/117/hr/3076</uri>
  </access_mcp_resource>
  

• Get Member Pelosi:

  <access_mcp_resource>
  <server_name>congress-server</server_name>
  <uri>congress-gov://member/P000197</uri>
  </access_mcp_resource>
  

• Get Info about 118th Congress:

  <access_mcp_resource>
  <server_name>congress-server</server_name>
  <uri>congress-gov://congress/118</uri>
  </access_mcp_resource>
  

• Get API Overview:

  <access_mcp_resource>
  <server_name>congress-server</server_name>
  <uri>congress-gov://info/overview</uri>
  </access_mcp_resource>
  

Using Tools

Use the use_mcp_tool command/method.

!!! CRITICAL TOOL WORKFLOW: Finding Entities & Getting Related Data !!!

Many common tasks require a mandatory two-step process using both tools:

1. STEP 1: Find the Entity ID using congress_search

   • Purpose: Locate the specific bill, member, committee, etc., you need and extract its unique identifier(s) (e.g., memberId, or the congress, billType, billNumber for a bill URI).

   • Tool: congress_search

   • Example: Find member "John Kennedy" (might return multiple results requiring selection):

     <use_mcp_tool>
       <server_name>congress-server</server_name>
       <tool_name>congress_search</tool_name>
       <arguments>
         {
           "collection": "member",
           "query": "John Kennedy"
         }
       </arguments>
     </use_mcp_tool>
     

   • Output: Look for the memberId (e.g., K000393) or other necessary identifiers in the results.

   • !!! WARNING !!! Searching might return multiple results. You MUST identify the correct entity and use its specific ID for the next step.

   • !!! API LIMITATION !!! Filtering general searches by congress using the filters parameter is NOT SUPPORTED by the underlying API (e.g., for /v3/bill or /v3/member) and will be ignored. Congress-specific filtering usually requires using specific API paths (e.g., /v3/bill/117), which this tool does not construct.

2. STEP 2: Get Related Data using congress_getSubResource

   • Purpose: Use the identifier(s) found in Step 1 to construct the parentUri and fetch related details (actions, sponsors, text, etc.).

   • Tool: congress_getSubResource

   • Prerequisite: You MUST have the correct parentUri (e.g., congress-gov://member/K000393) from Step 1.

   • Example: Get legislation sponsored by member K000393:

     <use_mcp_tool>
       <server_name>congress-server</server_name>
       <tool_name>congress_getSubResource</tool_name>
       <arguments>
         {
           "parentUri": "congress-gov://member/K000393",
           "subResource": "sponsored-legislation",
           "limit": 5
         }
       </arguments>
     </use_mcp_tool>
     

   • !!! GUARANTEED ERROR WARNING !!! You MUST use a subResource string that is STRICTLY VALID for the parentUri type (e.g., 'sponsored-legislation' for members, 'actions' for bills). Providing an invalid combination WILL cause an error. Check the tool description for valid combinations.

Following this two-step process is ESSENTIAL for reliably getting related information.

Tool Examples:

• Search for Bills containing "climate" (limit 5):

  <use_mcp_tool>
  <server_name>congress-server</server_name>
  <tool_name>congress_search</tool_name>
  <arguments>
  {
    "collection": "bill",
    "query": "climate",
    "limit": 5
  }
  </arguments>
  </use_mcp_tool>
  

• List Members (No Congress Filter Possible Here):

  • Note: As mentioned above, filtering by congress directly in congress_search is not supported by the API for the 'member' collection.

    <use_mcp_tool>
    <server_name>congress-server</server_name>
    <tool_name>congress_search</tool_name>
    <arguments>
    {
      "collection": "member",
      "limit": 10 
      // Add "query" or other filters like "type" if needed
    }
    </arguments>
    </use_mcp_tool>
    

• Get Actions for Bill H.R. 3076 (117th) (Requires URI from Search or Known Info):

  <use_mcp_tool>
  <server_name>congress-server</server_name>
  <tool_name>congress_getSubResource</tool_name>
  <arguments>
  {
    "parentUri": "congress-gov://bill/117/hr/3076",
    "subResource": "actions",
    "limit": 10
  }
  </arguments>
  </use_mcp_tool>
  

• Get Legislation Sponsored by Member P000197:

  <use_mcp_tool>
  <server_name>congress-server</server_name>
  <tool_name>congress_getSubResource</tool_name>
  <arguments>
  {
    "parentUri": "congress-gov://member/P000197",
    "subResource": "sponsored-legislation",
    "limit": 5
  }
  </arguments>
  </use_mcp_tool>
  

Linting and Formatting

• Lint: npm run lint
• Format: npm run format

Code will be automatically linted and formatted on commit via Husky and lint-staged.