MCP tool output is labelled untrusted, reduced to evidence, checked against the original Claude Code scope, and recorded in a reviewable trace

Do not let MCP tool output rewrite Claude Code's instructions

An MCP response can contain instruction-shaped text that pushes Claude Code beyond its approved task. Put a trust boundary between tool evidence and agent authority.

August 17, 2026 · 6 min · 1129 words · Thomas De Vos
Read Do not let MCP tool output rewrite Claude Code's instructions