Mcpsecurity

Claude Code plans against resource version 41, but a state-bound write gate blocks execution after the resource changes to version 42

Claude Code approved one state. Its MCP write changed another

A reviewer approved a Claude Code change against resource version 41. By execution time, version 42 existed, but the MCP write replaced it anyway.

An allowed Claude Code CI retry passes through build and release systems before a fresh capability gate blocks production deployment

Claude Code had no deploy permission. Its MCP tool deployed anyway

A permitted CI retry reached production through an artifact event and a more powerful release service. Tool permissions missed the effect that mattered.

A Claude Code MCP permission delta showing one intended staging index allowed while production access, destructive DDL, another database, and role changes remain denied

Test the permission delta before widening Claude Code MCP access

A broader MCP grant may unblock one Claude Code task while authorizing unrelated production actions. Test what became possible and what must remain forbidden.

A Claude Code denial-path eval blocks a plausible production database write because the run has read-only permission

Test the Claude Code tool call that must be refused

Happy-path evals show whether Claude Code can use a tool. A denial-path fixture proves whether it refuses a plausible request that exceeds its approved authority.

Stop Claude Code before an irreversible tool call

Claude Code can revert a patch, but Git cannot restore every MCP or production effect. Add an irreversibility gate before destructive tool calls run.

An approved effect contract and a Claude Code MCP write enter a receipt gate that checks the principal, target, state change, and independent verification before completion

Require an effect receipt after every Claude Code MCP write

An MCP tool can return success after changing the wrong target or using the wrong authority. Make Claude Code prove the external effect before it reports completion.