MetaMask MCP

Instructions

Implementation Reference

• src/tools/get-block.ts:18-46 (handler)

  The handler function that executes the get-block tool. It constructs parameters for wagmi's getBlock based on input args and returns the block data as a JSON string in MCP format.

  execute: async (args) => {
    const chainId = args.chainId as typeof wagmiConfig["chains"][number]["id"];
    const blockHash = args.blockHash;
    const blockNumber = args.blockNumber;
    const blockTag = args.blockTag;
  
    const parameters: GetBlockParameters = {
      chainId,
      includeTransactions: false,
    };
    if (blockHash) {
      parameters.blockHash = blockHash;
    }
    else if (blockNumber) {
      parameters.blockNumber = blockNumber;
    }
    else if (blockTag) {
      parameters.blockTag = blockTag;
    }
    const result = await getBlock(wagmiConfig, parameters);
    return {
      content: [
        {
          type: "text",
          text: JSONStringify(result),
        },
      ],
    };
  },

• src/tools/get-block.ts:12-17 (schema)

  Zod schema defining the input parameters (chainId, blockHash, blockNumber, blockTag) for the get-block tool.

  parameters: z.object({
    chainId: z.coerce.number().optional().describe("ID of chain to use when fetching data."),
    blockHash: Address.optional().describe("Information at a given block hash."),
    blockNumber: z.coerce.bigint().optional().describe("Information at a given block number."),
    blockTag: z.enum(["latest", "earliest", "pending", "safe", "finalized"]).optional().default("latest").describe("Information at a given block tag. Defaults to 'latest'."),
  }),

• src/tools/get-block.ts:9-47 (registration)

  The server.addTool call that registers the get-block tool with the MCP server, including name, description, schema, and handler.

  server.addTool({
    name: "get-block",
    description: "Fetch information about a block at a block number, hash or tag.",
    parameters: z.object({
      chainId: z.coerce.number().optional().describe("ID of chain to use when fetching data."),
      blockHash: Address.optional().describe("Information at a given block hash."),
      blockNumber: z.coerce.bigint().optional().describe("Information at a given block number."),
      blockTag: z.enum(["latest", "earliest", "pending", "safe", "finalized"]).optional().default("latest").describe("Information at a given block tag. Defaults to 'latest'."),
    }),
    execute: async (args) => {
      const chainId = args.chainId as typeof wagmiConfig["chains"][number]["id"];
      const blockHash = args.blockHash;
      const blockNumber = args.blockNumber;
      const blockTag = args.blockTag;
  
      const parameters: GetBlockParameters = {
        chainId,
        includeTransactions: false,
      };
      if (blockHash) {
        parameters.blockHash = blockHash;
      }
      else if (blockNumber) {
        parameters.blockNumber = blockNumber;
      }
      else if (blockTag) {
        parameters.blockTag = blockTag;
      }
      const result = await getBlock(wagmiConfig, parameters);
      return {
        content: [
          {
            type: "text",
            text: JSONStringify(result),
          },
        ],
      };
    },
  });

• src/tools/register-tools.ts:43-43 (registration)

  Invocation of registerGetBlockTools during the overall tools registration process.

  registerGetBlockTools(server, wagmiConfig);

• src/index.ts:15-15 (registration)

  Top-level call to register all tools, including get-block, in the main application entry point.

  registerTools(server, wagmiConfig);