mcp-hygienelisted

# MCP hygiene — query, persist, drop ## The problem Every MCP tool definition and every raw MCP result sits in the context window for the rest of the session. Ten "quick checks" against a DB server = thousands of stale tokens degrading everything after them. Context rot is architectural (attention is n²), so the fix is behavioral: **keep knowledge on disk, not in the window.** ## Rules 1. **Prefer a CLI or script over MCP when both exist.** `supabase db push --dry-run`, `gh pr view`, a `psql` one-liner, or a small script that writes its output to a file is deterministic and leaves ~zero residue. MCP is for interactive verification and for capabilities with no CLI equivalent. 2. **Query once, persist immediately.** The moment an MCP result matters beyond the current thought, write the distilled version to a file: - schema verification → append to the task's PROGRESS.md entry or a `notes/` scratch file - fetched reference data → a file in the repo (with provenance) Then work from the file, not from re-querying. 3. **Batch your questions.** Before calling, list everything you need from that server in this session. One structured query beats five conversational ones. 4. **Read-only by default.** Writes through MCP (DB mutations, posting, publishing) are forbidden unless the task file explicitly authorizes that exact write. Schema changes NEVER go through MCP (see `supabase-migration` skill). 5. **Verify-then-drop.** MCP's proper role in this harn