[BUG] Tool invocation failure for MCP tools post-compaction patch (Jan 27) — silent backend block on claude.ai

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?

January 27, 2026
Claude chat is unable to access any tools, inculding web search, Zapier, or other MCP connectors. We tried different things, but the key one that we're missing is the ability to read/write in Notion.

Affects web browser (claude.ai) and Claude Desktop app (updated today, January 27, 2026, after being broken for a day or two).

We had an issue earlier today with compaction failing unexpectedly at 95% multiple times, so started a new session. But the tool call is still not working.

I read this morning on Reddit from someone else with the same problem.

Max plan. Nowhere near limits.

What Should Happen?

Claude should be able to access Notion, read, write, create new pages.

Error Messages/Logs

Steps to Reproduce

Tried web searches, accessing Gmail, Notion...
Claude reports being able to see it, know how to access it, but feels a weird kind of resistance and just... can't execute it.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

claude.ai

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_