Bitcoin MCP Server

Instructions

Implementation Reference

• src/index.ts:268-323 (handler)

  The main execution handler for the 'get-transaction' tool. Fetches raw transaction data via helper and formats a detailed Markdown-like text response including basic info, status, inputs, and outputs.

  async ({ txid }) => {
    try {
      const tx = await getTransaction(txid);
  
      let result = `**Transaction: ${tx.txid}**\n\n`;
      result += `**Basic Info:**\n`;
      result += `- Version: ${tx.version}\n`;
      result += `- Size: ${tx.size} bytes\n`;
      result += `- Weight: ${tx.weight} WU\n`;
      result += `- Fee: ${tx.fee} sats\n`;
      result += `- Locktime: ${tx.locktime}\n\n`;
  
      result += `**Status:**\n`;
      if (tx.status.confirmed) {
        result += `- Confirmed in block ${tx.status.block_height}\n`;
        result += `- Block hash: ${tx.status.block_hash}\n`;
        result += `- Block time: ${new Date(tx.status.block_time! * 1000).toISOString()}\n`;
      } else {
        result += `- Unconfirmed (in mempool)\n`;
      }
      result += "\n";
  
      result += `**Inputs (${tx.vin.length}):**\n`;
      tx.vin.forEach((input, index) => {
        if (input.prevout) {
          result += `${index + 1}. ${input.txid.substring(0, 16)}...:${input.vout} - ${(input.prevout.value / 100000000).toFixed(8)} BTC\n`;
        } else {
          result += `${index + 1}. Coinbase transaction\n`;
        }
      });
      result += "\n";
  
      result += `**Outputs (${tx.vout.length}):**\n`;
      tx.vout.forEach((output, index) => {
        result += `${index + 1}. ${(output.value / 100000000).toFixed(8)} BTC to ${output.scriptpubkey_address || "Unknown address"}\n`;
      });
  
      return {
        content: [
          {
            type: "text",
            text: result,
          },
        ],
      };
    } catch (error: any) {
      return {
        content: [
          {
            type: "text",
            text: `Error fetching transaction data: ${error.message || "Unknown error"}`,
          },
        ],
      };
    }
  },

• src/index.ts:265-267 (schema)

  Zod input schema defining the 'txid' parameter for the tool.

  {
    txid: z.string().describe("Transaction ID (hash) to query"),
  },

• src/index.ts:262-324 (registration)

  Registration of the 'get-transaction' tool on the MCP server using server.tool() with name, description, schema, and handler.

  server.tool(
    "get-transaction",
    "Get detailed information about a Bitcoin transaction",
    {
      txid: z.string().describe("Transaction ID (hash) to query"),
    },
    async ({ txid }) => {
      try {
        const tx = await getTransaction(txid);
  
        let result = `**Transaction: ${tx.txid}**\n\n`;
        result += `**Basic Info:**\n`;
        result += `- Version: ${tx.version}\n`;
        result += `- Size: ${tx.size} bytes\n`;
        result += `- Weight: ${tx.weight} WU\n`;
        result += `- Fee: ${tx.fee} sats\n`;
        result += `- Locktime: ${tx.locktime}\n\n`;
  
        result += `**Status:**\n`;
        if (tx.status.confirmed) {
          result += `- Confirmed in block ${tx.status.block_height}\n`;
          result += `- Block hash: ${tx.status.block_hash}\n`;
          result += `- Block time: ${new Date(tx.status.block_time! * 1000).toISOString()}\n`;
        } else {
          result += `- Unconfirmed (in mempool)\n`;
        }
        result += "\n";
  
        result += `**Inputs (${tx.vin.length}):**\n`;
        tx.vin.forEach((input, index) => {
          if (input.prevout) {
            result += `${index + 1}. ${input.txid.substring(0, 16)}...:${input.vout} - ${(input.prevout.value / 100000000).toFixed(8)} BTC\n`;
          } else {
            result += `${index + 1}. Coinbase transaction\n`;
          }
        });
        result += "\n";
  
        result += `**Outputs (${tx.vout.length}):**\n`;
        tx.vout.forEach((output, index) => {
          result += `${index + 1}. ${(output.value / 100000000).toFixed(8)} BTC to ${output.scriptpubkey_address || "Unknown address"}\n`;
        });
  
        return {
          content: [
            {
              type: "text",
              text: result,
            },
          ],
        };
      } catch (error: any) {
        return {
          content: [
            {
              type: "text",
              text: `Error fetching transaction data: ${error.message || "Unknown error"}`,
            },
          ],
        };
      }
    },
  );

• src/index.ts:89-95 (helper)

  Helper function that fetches the raw Transaction data from the mempool.space API.

  async function getTransaction(txid: string): Promise<Transaction> {
    const res = await superagent
      .get(`${MEMPOOL_API_BASE}/tx/${txid}`)
      .set("User-Agent", USER_AGENT);
  
    return res.body;
  }

• src/index.ts:36-51 (schema)

  TypeScript interface defining the structure of a Transaction object used by the tool.

  type Transaction = {
    txid: string;
    version: number;
    locktime: number;
    vin: any[];
    vout: any[];
    size: number;
    weight: number;
    fee: number;
    status: {
      confirmed: boolean;
      block_height?: number;
      block_hash?: string;
      block_time?: number;
    };
  };