[Bug] Claude infers Slack workspace membership from URL subdomain without verification, presents unverifiable assumptions as facts

Bug Description
What happened?

The user asked Claude to determine Slack retention settings for RL run channels (#rl-*-runops, #prod-run-*). Claude inferred from anthropic.slack.com/archives/... URLs that the channels lived in the main Anthropic workspace and stated as fact that they "currently sit at 1 year" because runops/prod-run aren't on the trigger-word bot's 5-year list, leading the user to file ITOPS-27686 to add those trigger words. The channels actually live in the CSys workspace (blanket 5-year retention since Feb 2026); the URL subdomain doesn't indicate workspace membership in Enterprise Grid, and Claude presented an unverifiable inference as a checked finding instead of flagging "I can't see which workspace this channel is in."

Issue type

• Overconfidence
• Verification failures

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.72
• Feedback ID: e348099a-7ccf-4aa0-a364-503332fb1ae1

Errors

[{"error":"Error: Streamable HTTP error: Error POSTing to endpoint: event: message\r\ndata: {\"error\":\"upstream_connection_failure\",\"flag\":\"UF\",\"message\":\"Could not connect to upstream service. Verify the service is running and reachable.\",\"request_id\":\"1a551b64-9756-9994-8b05-5c0ec389a1a2\",\"request_url\":\"antmcp.forge.black.ant.dev/antmcp/google-workspace/mcp\",\"service\":\"antmcp\",\"timestamp\":\"2026-04-21T17:25:48.733Z\"}\r\n\r\n\n    at send (/$bunfs/root/src/entrypoints/cli.js:577:33615)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-21T17:25:49.140Z"},{"error":"AbortError: The operation was aborted.\n    at unknown\n    at abortChildProcess (node:child_process:935:42)\n    at onAbortListener2 (node:child_process:35:24)","timestamp":"2026-04-21T17:33:01.573Z"},{"error":"Error: ripgrep exited with code null\n    at <anonymous> (/$bunfs/root/src/entrypoints/cli.js:100:18219)\n    at emit (node:events:98:22)\n    at #maybeClose (node:child_process:766:16)\n    at #handleOnExit (node:child_process:520:72)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-21T17:33:01.578Z"},{"error":"TelemetrySafeError: Error executing tool sheets_update_values: sheets values.update 1av9aAjaRj52f7_OSSv_tsw9LUFNkQ24gumuKWgAsmkU!Spinups!N2: 503 Service Unavailable: {\"error\":\"upstream_connection_failure\",\"flag\":\"UF\",\"message\":\"Could not connect to upstream service. Verify the service is running and reachable.\",\"request_id\":\"12d5ffdc-df18-9879-850a-e356a99fd63e\",\"request_url\":\"antmcp.forge.black.ant.dev/outbound-proxy/https:/sheets.googleapis.com/v4/spreadsheets/1av9aAjaRj52f7_OSSv_tsw9LUFNkQ24gumuKWgAsmkU/values/Spinups%21N2?valueInputOption=USER_ENTERED\",\"service\":\"antmcp\",\"timestamp\":\"2026-04-21T17:36:50.478Z\"}\n\n    at y19 (/$bunfs/root/src/entrypoints/cli.js:6171:26837)\n    at async SnK (/$bunfs/root/src/entrypoints/cli.js:6171:23931)\n    at async call (/$bunfs/root/src/entrypoints/cli.js:6171:43424)\n    at async LvK (/$bunfs/root/src/entrypoints/cli.js:3904:15032)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-21T17:36:51.998Z"},{"error":"Error: Streamable HTTP error: Error POSTing to endpoint: event: message\r\ndata: {\"error\":\"upstream_connection_failure\",\"flag\":\"UF\",\"message\":\"Could not connect to upstream service. Verify the service is running and reachable.\",\"request_id\":\"59973ab5-763f-9610-84c3-901d770c195a\",\"request_url\":\"antmcp.forge.black.ant.dev/antmcp/google-workspace/mcp\",\"service\":\"antmcp\",\"timestamp\":\"2026-04-21T17:36:54.235Z\"}\r\n\r\n\n    at send (/$bunfs/root/src/entrypoints/cli.js:577:33615)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-21T17:36:55.625Z"},{"error":"Error: Streamable HTTP error: Error POSTing to endpoint: event: message\r\ndata: {\"error\":\"upstream_connection_failure\",\"flag\":\"UF\",\"message\":\"Could not connect to upstream service. Verify the service is running and reachable.\",\"request_id\":\"f5261466-f94f-9e0b-8404-9c8ad768711f\",\"request_url\":\"antmcp.forge.black.ant.dev/antmcp/google-workspace/mcp\",\"service\":\"antmcp\",\"timestamp\":\"2026-04-21T17:37:09.329Z\"}\r\n\r\n\n    at send (/$bunfs/root/src/entrypoints/cli.js:577:33615)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-21T17:37:11.182Z"},{"error":"Error: Streamable HTTP error: Error POSTing to endpoint: event: message\r\ndata: {\"error\":\"upstream_connection_failure\",\"flag\":\"UF\",\"message\":\"Could not connect to upstream service. Verify the service is running and reachable.\",\"request_id\":\"b9af0fe2-0096-9ca5-b34b-488666c9b0b0\",\"request_url\":\"antmcp.forge.black.ant.dev/antmcp/google-workspace/mcp\",\"service\":\"antmcp\",\"timestamp\"…

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