Reduce Mcp Tool Surface Footprint

The hosted MCP surface currently repeats the same cross-cutting guidance across many tool descriptions, producing a ~49.6 KB tools/list payload for 14 tools. That cost is paid by every MCP client session and sits in an unpredictable zone for chat-hosted clients whose exact tool-description and tool-result budgets are host-defined.

design-notes/mcp-tool-surface-token-footprint-2026-06-08.md measured the live hosted MCP tools/list response at ~49.6 KB, about ~12,400 tokens by the chars/4 estimate. The largest avoidable cost is repeated prose:

The MCP adapter SHALL publish compact server instructions during MCP initialization. The instructions SHALL carry cross-tool guidance that would otherwise be repeated across tool descriptions, including grant-scoped access posture, schema-first discovery, connection_id disambiguation, typed object filters, event-subscription preflight, and pagination/result narrowing.