Read-only MCP tools blocked in plan mode (refiling #12368, closed by stale-bot, not reviewed)
Problem
#12368 reported this. Bot auto-closed it after 60 days of silence, no maintainer ever responded. Issue is now locked, can't reopen or comment. Bug's still live.
Plan mode blocks every MCP tool call unless the tool is explicitly listed in permissions.allow. Applies even to pure reads: e.g. a search-only MCP tool that can't touch the codebase.
Error: Permission to use mcp__<server>__<tool> has been auto-denied in dontAsk mode.Plan mode's whole point is "explore without editing." A read-only MCP call doesn't break that. Blocking it anyway forces users into a blanket mcp__<server>__* allow rule just to get past planning. That rule then applies outside plan mode too, so it's not scoped permission, it's just a workaround.
Suggested approach
MCP tool defs already carry readOnlyHint. Claude Code already reads it for other things (permission-dialog grouping, parallel-call eligibility). Use it here too: auto-allow readOnlyHint: true tools while in plan mode, same as built-in read tools (Read, Grep, WebFetch) already are. Scope it to plan mode only, that's where "read-only" is the whole premise anyway.
Environment
- Claude Code v2.1.209, VS Code extension
- Related: #10801, #15551 (VS Code extension ignoring
permissions.allowfor MCP tools entirely), #25966 (same ask, broader scope, filed against Desktop) - Original: #12368, opened 2025-11-25, closed 2026-01-27 by inactivity bot, never reviewed by a person, now locked