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CLAIM C040 Supported 2026-11-06

GitHub issue #62072 in anthropics/claude-code, opened 2026-05-24 by Nubaeon, records a report that after auto-update to Claude Desktop 1.8555.2, Cowork sessions on macOS have zero MCP tools bound across all four install paths, that the Cowork VM spawner produces zero --mcp-config or --allowedTools args across 500 or more spawn events, that no .mcp.json is written into the session dirs, and that the Chat tab is unaffected with the same MCPs initializing cleanly there.

Verbatim Excerpts from Cited Records
“The Cowork VM spawner is producing zero `--mcp-config` / `--allowedTools` args:”
— Nubaeon · anthropics/claude-code (issue 62072 opening body, Root cause evidence section) · 2026-05-24T19:22:50Z ·GitHub Issue ↗
“No `.mcp.json` is being written into the session dirs either.”
— Nubaeon · anthropics/claude-code (issue 62072 opening body, Root cause evidence section) · 2026-05-24T19:22:50Z ·GitHub Issue ↗
“Symptom onset matches the auto-update window exactly.”
— Nubaeon · anthropics/claude-code (issue 62072 opening body, Timing match section) · 2026-05-24T19:22:50Z ·GitHub Issue ↗
“Ask the agent to list available tools → none of the MCP tools appear”
— Nubaeon · anthropics/claude-code (issue 62072 opening body, Steps to reproduce section) · 2026-05-24T19:22:50Z ·GitHub Issue ↗
Counter-record: Issue closed 2026-11-05 by github-actions bot for inactivity (not_planned); no maintainer resolution appears in the surveyed thread. The bot suggested duplicates #26259 and #36405 on 2026-05-24; the author contested the same day, arguing those describe an intermittent roughly 50/50 race while this is deterministic total loss across 500 or more spawns. The author reported a same-machine A/B on 2026-05-25 (downgrade to 1.3883.0 restored all MCP bindings) and fleet evidence on three machines on 2026-05-26. A second reporter confirmed the symptom on 1.9255.2 and 1.9659.2 (2026-05-28 and 2026-05-29), then reported on 2026-06-01 that a full reinstall cleared it on their end, suggesting local state corruption as a possible contributor. The author reported on 2026-07-01 that the symptom appeared resolved on 1.17377.1 after a clean-profile reinstall plus update, noting two variables changed at once so the load-bearing one cannot be isolated. Another commenter reported on 2026-07-11 and 2026-08-26 that the fix did not work on their machine, with the symptom still present on 1.20186.0 as of August 2026 and OAuth scope logs showing user:mcp_servers never requested. The claim documents only the original report, not a verified current state. Falsification probe: If issue 62072 is deleted without archive, if the author edits the opening body so the quoted sentences no longer match verbatim, or if the author posts a retraction of the report, this claim drops to Withdrawn. Audit verification: Verified 100% continuous verbatim substring against official GitHub REST API by scripts/verify_claim_verbatim.py.