Rider MCP tool schema mismatch with plugin v253.29346.144 (Rider 2025.3)

### Describe the bug

The built-in Rider MCP tool definitions in Copilot CLI v1.0.2 (prerelease v0.0.422-0) are incompatible with the JetBrains Rider MCP Server plugin version 253.29346.144 (Rider 2025.3).

Environment:
- Copilot CLI: v1.0.2 (GitHub.Copilot.Prerelease v0.0.422-0)
- Rider MCP plugin: 253.29346.144
- JetBrains Rider: 2025.3
- OS: Windows

### Affected version

Copilot CLI: v1.0.2 (GitHub.Copilot.Prerelease v0.0.422-0)

### Steps to reproduce the behavior

1. Install the Rider MCP Server plugin (v253.29346.144) in JetBrains Rider 2025.3
2. Add the Rider MCP server to ~/.copilot/mcp-config.json as an SSE server on http://localhost:64342/sse
3. Start a Copilot CLI session
4. Attempt to use any Rider MCP tool (e.g., get open files, get project modules)

### Expected behavior

Expected result: Rider MCP tools respond successfully and return project/file information.

Actual result:

McpError: MCP error -32602: Structured content does not match the tool's output schema: data must have required property 'openFiles'
McpError: MCP error -32602: Structured content does not match the tool's output schema: data must have required property 'modules'

### Additional context

_No response_