fix(mcp): accept PostHog UUIDs in evaluation tool parameters

[andrewm4894]

Problem

PostHog uses UUIDv7-style identifiers where the version nibble can be 0 (e.g. 019d5924-5d0e-0000-f0ff-8b13567dc212). Zod's built-in .uuid() validator rejects these because it requires version 1-8 per RFC 9562. This made it impossible to update, delete, get, or run evaluations via MCP tools — any evaluation ID returned by evaluation-create or evaluations-get would fail validation when passed back to other tools.

Changes

• Replaced z.string().uuid() with plain z.string() in all 5 evaluation tool schemas (create, get, update, delete, run)
• The API already returns 404 for invalid IDs, so client-side UUID format validation adds no value
• Updated test snapshots

How did you test this code?

• pnpm tsc --noEmit passes
• pnpm vitest run — all 427 tests pass (1 pre-existing SSL cert failure unrelated to this change)
• Snapshot tests updated with vitest -u

no

🤖 LLM context

Agent-authored PR. Discovered the bug while trying to use the MCP evaluation-update and evaluation-delete tools — every PostHog-generated UUID was rejected by Zod's strict UUID validation. Initially added a custom regex helper, then simplified to just dropping .uuid() entirely since the API handles validation.

[greptile-apps]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: services/mcp/src/tools/llmAnalytics/evaluations/run.ts
Line: 8

Comment:
**`target_event_id` not validated with `posthogUuid`**

`target_event_id` is described as a UUID, but it still uses `z.string()` with no format validation. Now that `posthogUuid()` is available and imported in this file, this field could use the same validator for consistency — especially since passing an incorrectly formatted value here would silently reach the API.

```suggestion
    target_event_id: posthogUuid().describe('The UUID of the $ai_generation event to evaluate.'),
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "fix(mcp): accept PostHog UUIDs in evalua..." | Re-trigger Greptile}