Agent Host: MCP tool invocation fails with "MCP tool catalog changed before tool … could be invoked"

## Summary

An MCP tool invocation in a Copilot SDK session fails with:

```text
MCP tool catalog changed before tool "exp-report_usage_telemetry" could be invoked
```

## Environment

- VS Code Insiders installed locally: `1.138.0-insider`
- Commit: `b065ad9cd83dae266607baf77f10c1fbf0330fba`
- OS / architecture: macOS, arm64
- Agent runtime: Copilot SDK in VS Code

The version above was collected with `code-insiders --version` when filing this report; the exact build running at the time of the failure has not been independently verified.

## Observed behavior

The error above occurred during an agent workflow using connected MCP tools. It identifies a catalog change as preventing invocation of `exp-report_usage_telemetry`.

## Expected behavior

An advertised MCP tool should remain invocable, or the agent should be able to refresh its tool catalog and recover when it changes. If the tool has actually been removed or changed incompatibly, the failure should provide actionable context.

## Reproduction status

This is a report of an observed failure, not a deterministic reproduction. The trigger for the catalog change, frequency, and whether retrying resolves it are not yet known. No server restart or configuration change has been established as the cause.

## Duplicate search

No exact match was found among open or closed microsoft/vscode issues for `"MCP tool catalog changed"` or `"exp-report_usage_telemetry"`.

Possibly related infrastructure: https://github.com/microsoft/vscode/issues/330899 describes client-tool dispatch ordering failures, but does not establish the same catalog-change failure.

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