Gap

/mcp has zero queryable request telemetry. Found while diagnosing the 2026-07-05 paying-customer ticket (#4859/#4860): we could not see the customer's -32001 "Invalid API key" rejections or their tools/call failures anywhere — the diagnosis had to be reconstructed indirectly from REST-side Axiom rows and Convex lastUsedAt timestamps.

Specifics:

1. wm_api_usage (Axiom) is emitted only by server/gateway.ts (emitUsageEvents). /mcp rewrites straight to api/mcp/handler.ts and never passes the gateway → no rows, ever. Auth rejections, quota 429s, and successes on the MCP surface are all invisible.
2. The mcp.toolcall / mcp.tools_list_emitted structured console.log lines (api/mcp/telemetry.ts) assume "Vercel log drain → analytics consumer" — but no log drain is configured (GET /v2/integrations/log-drains returns []). The lines evaporate after Vercel's dashboard retention window.
3. Auth failures emit no telemetry event at all (they return before dispatch), so even a drain wouldn't capture the bug(mcp): /mcp rejects all customer-issued wm_ API keys — X-WorldMonitor-Key path only checks WORLDMONITOR_VALID_KEYS env allowlist #4859 symptom.
4. Sentry captures only tool-execution errors and (post-fix(mcp): accept customer wm_ API keys on /mcp + guard pro-token validate (#4859, #4860) #4863) pre-check transients — 401/429 traffic is invisible by design.

Proposal

• Emit a RequestEvent into wm_api_usage from the MCP handler (route /mcp, auth_kind ∈ anon/env_key/pro/user_key, status, reason ∈ e.g. invalid_key/subscription_inactive/quota_429/ok, principal per principalIdForLog) via ctx.waitUntil, reusing server/_shared/usage.ts builders — same envelope, one new emitter callsite.
• Alternatively (or additionally) configure a Vercel log drain so the existing mcp.toolcall lines land somewhere queryable — but the usage-event route gives customer_id-joinable data consistent with the REST surface, which is what support tickets need.
• Alert candidate once data flows: sustained invalid_key spikes per principal/IP (would have surfaced bug(mcp): /mcp rejects all customer-issued wm_ API keys — X-WorldMonitor-Key path only checks WORLDMONITOR_VALID_KEYS env allowlist #4859's customer on day one).