Opentrons MCP Server

Instructions

Implementation Reference

• index.js:1982-2013 (handler)

  The handler function that executes the tool logic by making a POST request to the robot's /robot/lights endpoint with the 'on' parameter.

  async controlLights(args) {
    const { robot_ip, on } = args;
    
    try {
      const body = { on };
      
      const data = await this.makeApiRequest(
        'POST',
        `http://${robot_ip}:31950/robot/lights`,
        { 'Content-Type': 'application/json' },
        JSON.stringify(body)
      );
      
      return {
        content: [
          {
            type: "text",
            text: `✅ Lights turned ${on ? 'ON' : 'OFF'} successfully!`
          }
        ]
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: `❌ Failed to control lights: ${error.message}`
          }
        ]
      };
    }
  }

• index.js:198-209 (schema)

  The tool schema definition provided in the ListTools response, specifying name, description, and input schema.

  {
    name: "control_lights",
    description: "Turn robot lights on or off",
    inputSchema: {
      type: "object",
      properties: {
        robot_ip: { type: "string", description: "Robot IP address" },
        on: { type: "boolean", description: "True to turn lights on, false to turn off" }
      },
      required: ["robot_ip", "on"]
    }
  },

• index.js:264-265 (registration)

  Registration of the tool handler in the CallToolRequestSchema switch statement.

  case "control_lights":
    return this.controlLights(args);

• index.js:483-495 (helper)

  API endpoint documentation for POST /robot/lights used by the control_lights tool.

  {
    method: "POST",
    path: "/robot/lights",
    summary: "Control lights",
    description: "Turn rail lights on or off",
    tags: ["Control"],
    requestBody: {
      required: true,
      properties: {
        on: { type: "boolean", description: "True to turn lights on, false to turn off" }
      }
    }
  },