Read-only MCP was easy: 5 rules for letting agents write safely
ainexfinder · reddit · 2026-10-12
A team shares what changed when their MCP agents went from read-only (search, fetch, summarize) to write access (updating tickets, editing rows, sending things). Their key insight: most incidents weren't the model being dumb — they were overly broad scopes and invisible writes. Their five rules: (1) separate read/write scopes per tool, never one token for both; (2) show a dry-run diff for human approval until an action has a clean track record; (3) cap blast radius with max rows/files per call, failing closed above the cap; (4) log who approved what with the exact payload; (5) no undo path means no unattended write — a human stays in the loop.
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