Azure MCP learn=true calls time out after 180s in Copilot CLI 1.0.83-5

Copilot CLI の MCP 階層型ツールディスカバリーパスから開始し、報告された Azure 呼び出しをバージョン 1.0.83-5 と 1.0.80 で learn=true を付けて再現します。直接の子コマンド呼び出しが引き続き成功することを確認しながらディスカバリーの動作を比較します。完了条件は、両方の階層プローブが 180 秒後にタイムアウトするのではなく、スキーマを速やかに返すことです。

Describe the bug

Azure MCP hierarchical tool discovery calls using learn=true consistently time out after 180 seconds in Copilot CLI 1.0.83-5. The same calls complete in about 0.2 seconds under CLI 1.0.80.

Direct Azure MCP child-command calls without learn=true still succeed, which isolates the regression to hierarchical tool discovery rather than MCP startup, authentication, or general Azure connectivity.

Affected version

GitHub Copilot CLI 1.0.83-5
Windows executable file/product version: 1.0.83-5

Steps to reproduce the behavior

1. Configure the Microsoft Azure MCP server and confirm it connects.
2. Start Copilot CLI 1.0.83-5.
3. Ask the agent to make exactly one Azure Kusto MCP call with: {"intent":"Discover the Kusto command contract","learn":true}
4. Observe that the call remains pending for 180 seconds and fails with: MCP server 'azure': McpError: MCP error -32001: Request timed out
5. Repeat with Azure get_azure_bestpractices and learn=true; it fails the same way.
6. Run the same probes with CLI 1.0.80; both discovery calls succeed immediately.

Controlled A/B results:

The fresh Kusto and Best Practices A/B probes were launched simultaneously under both CLI versions with the same model, workspace, MCP configuration, and machine. All probe stderr logs were empty.

Expected behavior

learn=true should return the hierarchical tool command schema promptly, as it does under CLI 1.0.80, instead of reaching the client's 180-second timeout.

Additional context

• OS: Windows 11 Enterprise 23H2, build 22631
• Architecture: AMD64
• Shell: PowerShell 7.6.5
• Terminal: VS Code integrated terminal
• Azure MCP reached connected before each probe
• Reproduced 3/3 times on 1.0.83-5
• Control succeeded 3/3 times on 1.0.80
• No exact duplicate found in the open or closed github/copilot-cli issues