ChainFETCH MCP Server

Instructions

Implementation Reference

• index.js:707-708 (handler)

  The handler case for 'search_transactions_json' tool that executes the tool logic by calling makeRequest to the ChainFETCH API endpoint '/api/v1/ethereum/transactions/json_search'.

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

• index.js:170-225 (registration)

  Registration of the 'search_transactions_json' tool in the ListTools response, including its name, description, and input schema.

  {
    name: 'search_transactions_json',
    description: 'JSON search for transactions with 254+ carefully curated parameters',
    inputSchema: {
      type: 'object',
      properties: {
        hash: {
          type: 'string',
          description: 'Transaction hash',
        },
        value_min: {
          type: 'string',
          description: 'Minimum transaction value in WEI',
        },
        value_max: {
          type: 'string',
          description: 'Maximum transaction value in WEI',
        },
        gas_used_min: {
          type: 'string',
          description: 'Minimum gas used',
        },
        gas_used_max: {
          type: 'string',
          description: 'Maximum gas used',
        },
        from_hash: {
          type: 'string',
          description: 'From address hash',
        },
        to_hash: {
          type: 'string',
          description: 'To address hash',
        },
        block_number_min: {
          type: 'integer',
          description: 'Minimum block number',
        },
        block_number_max: {
          type: 'integer',
          description: 'Maximum block number',
        },
        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:173-224 (schema)

  Input schema definition for the 'search_transactions_json' tool, defining parameters for JSON-based transaction search.

  inputSchema: {
    type: 'object',
    properties: {
      hash: {
        type: 'string',
        description: 'Transaction hash',
      },
      value_min: {
        type: 'string',
        description: 'Minimum transaction value in WEI',
      },
      value_max: {
        type: 'string',
        description: 'Maximum transaction value in WEI',
      },
      gas_used_min: {
        type: 'string',
        description: 'Minimum gas used',
      },
      gas_used_max: {
        type: 'string',
        description: 'Maximum gas used',
      },
      from_hash: {
        type: 'string',
        description: 'From address hash',
      },
      to_hash: {
        type: 'string',
        description: 'To address hash',
      },
      block_number_min: {
        type: 'integer',
        description: 'Minimum block number',
      },
      block_number_max: {
        type: 'integer',
        description: 'Maximum block number',
      },
      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:634-682 (helper)

  Helper function 'makeRequest' that performs HTTP requests to the ChainFETCH API, used by all tool handlers including search_transactions_json.

  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();
  }