MCP Background Task Server

Instructions

Implementation Reference

• src/index.ts:261-297 (handler)

  The handler function for the 'send-to-task-stdin' tool. It retrieves the Child process by task name from the processes Map, and calls writeToStdin(data) on it, returning success or error message.

    async ({ name, data }) => {
      const child = processes.get(name);
      if (!child) {
        return {
          content: [
            {
              type: "text",
              text: `No task found with name "${name}".`,
            },
          ],
        };
      }
  
      try {
        child.writeToStdin(data);
        return {
          content: [
            {
              type: "text",
              text: `Data sent to task "${name}" stdin.`,
            },
          ],
        };
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: `Failed to send data to task "${name}" stdin: ${
                error instanceof Error ? error.message : String(error)
              }`,
            },
          ],
        };
      }
    }
  );

• src/index.ts:253-260 (schema)

  The schema definition for the 'send-to-task-stdin' tool, including title, description, and inputSchema using Zod for name and data parameters.

  {
    title: "Send to Task Stdin",
    description: "Sends data to the stdin of a running background task.",
    inputSchema: {
      name: z.string().describe("Unique name of the task"),
      data: z.string().describe("Data to send to the task's stdin"),
    },
  },

• src/index.ts:251-297 (registration)

  The server.registerTool call that registers the 'send-to-task-stdin' tool with its schema and handler function.

  server.registerTool(
    "send-to-task-stdin",
    {
      title: "Send to Task Stdin",
      description: "Sends data to the stdin of a running background task.",
      inputSchema: {
        name: z.string().describe("Unique name of the task"),
        data: z.string().describe("Data to send to the task's stdin"),
      },
    },
    async ({ name, data }) => {
      const child = processes.get(name);
      if (!child) {
        return {
          content: [
            {
              type: "text",
              text: `No task found with name "${name}".`,
            },
          ],
        };
      }
  
      try {
        child.writeToStdin(data);
        return {
          content: [
            {
              type: "text",
              text: `Data sent to task "${name}" stdin.`,
            },
          ],
        };
      } catch (error) {
        return {
          content: [
            {
              type: "text",
              text: `Failed to send data to task "${name}" stdin: ${
                error instanceof Error ? error.message : String(error)
              }`,
            },
          ],
        };
      }
    }
  );

• src/index.ts:49-55 (helper)

  The writeToStdin method in the Child class, which performs the actual writing to the child process's stdin using Node.js child_process.stdin.write.

  public writeToStdin(data: string): void {
    if (this.process.stdin) {
      this.process.stdin.write(data);
    } else {
      throw new Error("Child process stdin is not available.");
    }
  }