Tier MCP rate limits by mutation risk, not a single human-calibrated ceiling

Digital Applied·medium signal

A '60 requests/minute' cap tuned for humans collapses against an agent issuing hundreds of calls at an expensive or state-mutating tool. The fix is per-tool, per-caller (token identity) buckets: read/cheap tools ~1000/min, mutating/expensive tools ~10/min, with burst allowances that differ by class. This converts rate limiting from a blunt global knob into a blast-radius control matched to each tool's actual cost and danger.