I cut my MCP server from 8 tools to 5 and the hallucinations stopped

Shipped @gitdealflow/mcp-signal with 8 tools mirroring REST endpoints. Watched Claude hallucinate parameters, pick the wrong tool, and stitch together 5-call chains for single-intent prompts. Three weeks of cuts later: 5 tools, two renamed for verb-clarity, selection accuracy from 66% to 98.5%, average tool calls per intent from 2.4 to 1.1. The heuristic: design one tool per user intent, not one per resource. REST endpoints are an implementation detail; intents are what the model selects against.

Key stats

98.5%: First-call selection accuracy after the cuts (Up from 66% on the 8-tool menu, measured on 200 real prompts.)

1.1: Average tool calls per user intent (Down from 2.4 before. Most prompts now resolve in a single call.)

~2,200: Input tokens saved per turn from menu trim (Eight schemas at ~600 tokens each became five at ~560 each.)