ChainFETCH MCP Server

Instructions

Implementation Reference

• index.js:288-338 (registration)

  Registration of the search_blocks_json tool, including its description and input schema definition.

  {
    name: 'search_blocks_json',
    description: 'JSON search for blocks with 120+ parameters',
    inputSchema: {
      type: 'object',
      properties: {
        hash: {
          type: 'string',
          description: 'Block hash',
        },
        height_min: {
          type: 'integer',
          description: 'Minimum block height',
        },
        height_max: {
          type: 'integer',
          description: 'Maximum block height',
        },
        gas_used_min: {
          type: 'string',
          description: 'Minimum gas used',
        },
        gas_used_max: {
          type: 'string',
          description: 'Maximum gas used',
        },
        transaction_count_min: {
          type: 'integer',
          description: 'Minimum transaction count',
        },
        transaction_count_max: {
          type: 'integer',
          description: 'Maximum transaction count',
        },
        miner_hash: {
          type: 'string',
          description: 'Miner address hash',
        },
        limit: {
          type: 'integer',
          description: 'Number of results to return (default: 10, max: 50)',
          default: 10,
        },
        offset: {
          type: 'integer',
          description: 'Number of results to skip for pagination (default: 0)',
          default: 0,
        },
      },
      required: [],
    },

• index.js:724-725 (handler)

  Handler case for search_blocks_json tool that delegates to the makeRequest helper to call the ChainFETCH API endpoint.

  case 'search_blocks_json':
    return await this.makeRequest('/api/v1/ethereum/blocks/json_search', 'GET', args, null, token);

• index.js:634-682 (helper)

  Shared helper function makeRequest used by all tools, including search_blocks_json, to make authenticated API requests to ChainFETCH endpoints.

  async makeRequest(endpoint, method = 'GET', params = {}, body = null, token = null) {
    const chainfetchToken = token || process.env.CHAINFETCH_API_TOKEN;
    
    if (!chainfetchToken) {
      throw new McpError(
        ErrorCode.InvalidRequest,
        'CHAINFETCH_API_TOKEN is required'
      );
    }
  
    const url = new URL(`${API_BASE_URL}${endpoint}`);
    
    // Add query parameters for GET requests
    if (method === 'GET' && Object.keys(params).length > 0) {
      Object.entries(params).forEach(([key, value]) => {
        if (value !== undefined && value !== null) {
          if (Array.isArray(value)) {
            value.forEach(v => url.searchParams.append(`${key}[]`, v));
          } else {
            url.searchParams.append(key, value.toString());
          }
        }
      });
    }
  
    const fetchOptions = {
      method,
      headers: {
        'Authorization': `Bearer ${chainfetchToken}`,
        'Content-Type': 'application/json',
      },
    };
  
    if (body && method !== 'GET') {
      fetchOptions.body = JSON.stringify(body);
    }
  
    const response = await fetch(url.toString(), fetchOptions);
    
    if (!response.ok) {
      const errorText = await response.text();
      throw new McpError(
        ErrorCode.InternalError,
        `API request failed: ${response.status} ${response.statusText} - ${errorText}`
      );
    }
  
    return await response.json();
  }