Arbitrum MCP Server

Instructions

Implementation Reference

• src/index.ts:560-577 (handler)

  The MCP tool handler implementation for 'arbtrace_get'. It resolves the RPC URL from chainName or rpcUrl, creates a NitroNodeClient instance, calls its traceGet method with the provided txHash and path, and returns the result as JSON text content.

  case "arbtrace_get": {
    const rpcUrl = await this.resolveRpcUrl(
      (args.rpcUrl as string) || (args.chainName as string)
    );
    const nodeClient = new NitroNodeClient(rpcUrl);
    const result = await nodeClient.traceGet(
      args.txHash as string,
      (args.path as string[]) || []
    );
    return {
      content: [
        {
          type: "text",
          text: JSON.stringify(result, null, 2),
        },
      ],
    };
  }

• src/index.ts:1323-1351 (registration)

  Registration of the 'arbtrace_get' tool in the getAvailableTools() method, which is returned in response to listTools requests. Includes the tool name, description, and input schema definition.

    name: "arbtrace_get",
    description:
      "Get specific trace data at a given path within a transaction (requires trace API)",
    inputSchema: {
      type: "object" as const,
      properties: {
        rpcUrl: {
          type: "string",
          description:
            "The RPC URL of the Arbitrum node (optional if default is set)",
        },
        chainName: {
          type: "string",
          description:
            "Chain name (e.g., 'Xai', 'Arbitrum One') - will auto-resolve to RPC URL",
        },
        txHash: {
          type: "string",
          description: "Transaction hash",
        },
        path: {
          type: "array",
          description: "Path to specific trace data",
          items: { type: "string" },
        },
      },
      required: ["txHash"],
    },
  },

• src/clients/nitro-node-client.ts:311-323 (helper)

  Supporting method in NitroNodeClient that performs the actual 'arbtrace_get' RPC call to the Arbitrum node with txHash and path parameters, handling errors and returning TraceResult.

  async traceGet(txHash: string, path: string[]): Promise<TraceResult> {
    try {
      const traces = await this.makeRpcCall("arbtrace_get", [txHash, path]);
      return { traces };
    } catch (error) {
      return {
        traces: null,
        error: `Trace get not supported on this RPC endpoint: ${
          (error as Error).message
        }`,
      };
    }
  }