Claude Desktop 1.24012.1 on Windows stops sending MCP `tools/call` requests
DFNR2026 · ghdev · 2026-07-22
Claude Desktop on Windows MSIX stops sending tools/call to MCP servers
A bug report against anthropics/claude-code says that after upgrading to Claude Desktop 1.24012.1 on Windows, MCP servers still complete initialize and tools/list, but never receive any tools/call messages. The affected filesystem connector then fails every invocation with a generic “Failed to call tool” error.
Key points from the report:
- Reproducible on Windows 10 x64 with the MSIX build from claude.com.
- The filesystem server starts normally and the handshake completes.
- Logs show no tools/call traffic at all.
- The issue appears immediately after the update and breaks all projects using the Filesystem connector.
- The screenshot attached to the issue confirms it is the Claude Desktop Windows regression report.
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