[BUG] Excel Integration: "When responding to programmatic tool calling, only tool_result blocks are allowed" error after extended operation

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

aWhen using the Claude Excel integration (beta) for an extended period, Claude stops functioning and returns the error:

"When responding to programmatic tool calling, only tool_result blocks are allowed"

This occurs consistently after a few minutes of operation, particularly when performing complex data manipulation tasks. In my case, I asked Claude to consolidate data and create an insights tab, and after running for a while, it crashed with this error message.

The error appears to be related to how the Excel integration handles tool calling responses after extended use, possibly a timeout or state management issue.

What Should Happen?

aClaude should continue to operate normally regardless of session duration. The Excel integration should handle extended operations (multiple minutes) without crashing or throwing tool calling errors. Complex data manipulation tasks should complete successfully without interruption.

Error Messages/Logs

When responding to programmatic tool calling, only tool_result blocks are allowed.

Steps to Reproduce

a1. Install the latest Claude Excel integration (beta)

1. Open Excel and activate the Claude integration
2. 3. Load a workbook with data that requires complex manipulation
3. 4. Ask Claude to perform an extended operation (e.g., "consolidate data and create insights tab")
4. 5. Wait for a few minutes while Claude processes the request
5. 6. Error appears: "When responding to programmatic tool calling, only tool_result blocks are allowed"
6. 7. Claude stops functioning and cannot continue

Note: This error occurs consistently after a few minutes of operation, suggesting a timeout or state management issue in the Excel integration's tool calling mechanism.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Latest Claude Excel Integration (Beta) - Version unknown

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_