Power Platform Community Forum Thread Details

Copilot Studio successfully authenticates with our MCP (Model Context Protocol) server using API Key authentication, completes the MCP handshake, but fails to make a follow up call for 'tools/list' which results in no tools being discovered in Copilot.

Current Behavior

1. ✅ Copilot Studio successfully authenticates
2. ✅ MCP handshake completes normally
3. ❌ No tools are discovered or available in Copilot Studio
4. ❌ No follow-up tools/list requests are made

Complete Request/Response Flow

Request 1: Initialize
Copilot Studio → MCP Server

  {
    "jsonrpc": "2.0",
    "id": "1",
    "method": "initialize",
    "params": {
      "capabilities": {},
      "clientInfo": {
        "agentName": "Sales Assistant",
        "appId": "redacted",
        "cdsBotId": "redacted",
        "channelId": "pva-studio",
        "name": "mcs",
        "version": "1.0.0"
      },
      "protocolVersion": "2024-11-05",
      "sessionContext": {}
    }
  }

MCP Server → Copilot Studio

  {
    "jsonrpc": "2.0",
    "id": "1",
    "result": {
      "protocolVersion": "2024-11-05",
      "capabilities": {
        "tools": {
          "listChanged": true
        },
        "resources": {
          "listChanged": true
        },
        "prompts": {
          "listChanged": true
        }
      },
      "serverInfo": {
        "name": "smcp-server",
        "version": "1.0.0",
        "description": "MCP server for database operations"
      }
    }
  }

Request 2: Notifications/Initialized
Copilot Studio → MCP Server

  Copilot Studio → MCP Server
  {
    "jsonrpc": "2.0",
    "method": "notifications/initialized"
  }

MCP Server → Copilot Studio
null

Questions for the community:

1. Tool Discovery Protocol: Does Copilot Studio expect tools to be:
- A) Embedded directly in the initialize response, OR
- B) Discovered via separate tools/list requests after handshake?
2. Required Tool Format: What is the exact JSON schema/format Copilot Studio expects for tool definitions?
3. Debugging: Are there any Copilot Studio logs or debugging options to see why tools aren't being recognized?
4. MCP Compatibility: Does Copilot Studio fully support the MCP 2024-11-05 specification, or are there Copilot-specific requirements?

What We've Tried

- ✅ API Key authentication (working)
- ✅ Standard MCP protocol handshake (working)
- ✅ Proper JSON-RPC 2.0 format (working)
- ✅ MCP protocol version 2024-11-05 (working)
- ❌ Tool discovery (not working)

Expected Behavior

After the MCP handshake completes, Copilot Studio should either:

1. Display the tools that were embedded in the initialize response, OR
2. Send a tools/list request to discover available tools

Additional Context

- The same MCP server works perfectly with direct API calls
- All 6 tools are properly registered and functional
- Authentication and basic MCP communication work flawlessly
- The issue is specifically with tool discovery/recognition

Any guidance on the correct tool discovery protocol for Copilot Studio would be greatly appreciated!

Categories:

Model context protocol

Hi,

Based on the behavior you've described, it seems that Copilot Studio expects tool discovery to occur via a **separate `tools/list` request** after the MCP handshake, not embedded directly in the `initialize` response. This aligns with the MCP 2024-11-05 specification, where `listChanged: true` flags the client to initiate follow-up discovery calls.

A few things to verify:

- **Request ID format**: Ensure the `"id"` field in your JSON-RPC responses is a **string**, not a number. Some clients strictly enforce this.
- **Tool schema**: Each tool should be defined with a clear `name`, `description`, and a valid `inputSchema`. Here's a minimal example:
```json
{
"name": "get_weather",
"description": "Returns weather data for a location",
"inputSchema": {
"type": "object",
"properties": {
"location": {
"type": "string"
}
},
"required": ["location"]
}
}
```
- **Logging**: If you're using VS Code, you can inspect the MCP server logs via `List Servers > [your server] > Show Output`. Also, make sure your server logs to `stderr` rather than `stdout`, as stdout is reserved for protocol communication.

If the `tools/list` call is not being triggered, it may be due to a subtle incompatibility in the `initialize` response or a missing capability flag. You might also want to cross-check with the [official MCP documentation](https://modelcontextprotocol.io/specification/2024-11-05/server/tools) and Copilot Studio integration guide for any Copilot-specific nuances.

Please let me know if this resolves your issue by marking the response as helpful.

Thanks and best regards,
Daniele
*Note: This response was prepared with support from Copilot to ensure clarity and completeness.*