Toolset not listing for Github MCP Server | Unstable behaviour of test chat pannel in copilot studio

### Description
I'm experiencing a tool discovery failure when connecting the GitHub MCP Server to a Copilot Studio agent. The connection authenticates successfully (green status in UI), but the Tools and Resources sections show "No tools available" and "No resources available," preventing the agent from accessing actions like `get_file_contents` or `search_code`. This blocks integration for code retrieval in my internal agent.

The server endpoint appears to connect, but the discovery response (e.g., `/mcp/sse` or `/mcp`) is not returning the expected YAML/OpenAPI schema with a populated `tools` array, leading to an empty list in Copilot Studio.

### Expected Behavior
- After connection, the Tools section should list 20-30 GitHub actions (e.g., `get_file_contents: Get the contents of a file or directory from a GitHub repository`, `search_code`, `list_branches`).
- Resources should populate with repo metadata (e.g., contents as readable blobs).
- Agent prompts should invoke tools without SystemError (e.g., successful code fetch).

### Actual Behavior
- Tools/Resources: Empty lists ("No tools available").
- Agent test: "Sorry, something went wrong. Error code: SystemError."
- No discovery response in Activity logs—endpoint returns 200 but empty schema.