Greptile Summary

This PR fixes a real crash path where MCP tools with no parameters produce { type: "object" } schemas (without a properties field), which the OpenAI Responses API silently rejects — taking down entire sessions. The fix injects properties: {} in both normalization paths (normalizeToolParameters in pi-tools.schema.ts and convertTools in openai-ws-message-conversion.ts), and adds targeted test coverage for both paths.

Changes:

• src/agents/pi-tools.schema.ts: New branch in normalizeToolParameters() to inject properties: {} for schemas that have type but lack properties, placed correctly before the anyOf/oneOf union-flattening block.
• src/agents/openai-ws-message-conversion.ts: convertTools() now checks and normalizes bare object schemas before forwarding to the OpenAI Responses API. This path correctly guards with params.type === \"object\".
• src/agents/pi-tools.schema.test.ts / src/agents/openai-ws-stream.test.ts: Five new test cases with good coverage of the injection, preservation, and additionalProperties scenarios.

Minor note: The condition in normalizeToolParameters checks \"type\" in schema (any type value) rather than schema.type === \"object\" as the convertTools path does. Top-level MCP tool schemas are always objects in practice, so this won't cause a real bug today, but aligning the guard would be more defensive.

Confidence Score: 5/5

Safe to merge — the fix directly addresses a confirmed crash and all remaining feedback is a minor style suggestion.

The fix is correct and well-targeted. Both normalization paths are covered by tests. The only finding is a P2 inconsistency: normalizeToolParameters does not restrict the properties: {} injection to schema.type === "object" the way convertTools does, which could theoretically inject invalid JSON Schema into non-object-typed schemas. In practice this path is unreachable since MCP tools always produce object schemas at the top level, so it does not block merge.

No files require special attention beyond the minor guard tightening noted in src/agents/pi-tools.schema.ts.

This is a comment left during a code review.
Path: src/agents/pi-tools.schema.ts
Line: 139-150

Comment:
**Missing `type === "object"` guard — inconsistency with `convertTools`**

The sibling fix in `convertTools` explicitly narrows the injection to `params.type === "object"`:

```ts
params.type === "object" && !("properties" in params)
```

The condition added here is broader — it fires for *any* schema that has a `type` field but no `properties` field, including `{ type: "string" }`, `{ type: "array" }`, etc. For those non-object types, injecting `properties: {}` would produce invalid JSON Schema.

In practice all top-level tool schemas coming from MCP are `type: "object"`, so this is unlikely to cause a real-world bug today, but adding the narrower guard keeps the two paths consistent and future-proof:

```suggestion
  if (
    "type" in schema &&
    schema.type === "object" &&
    !("properties" in schema) &&
    !Array.isArray(schema.anyOf) &&
    !Array.isArray(schema.oneOf)
  ) {
    const schemaWithProperties = { ...schema, properties: {} };
    return preserveToolMeta({
      ...tool,
      parameters: applyProviderCleaning(schemaWithProperties),
    });
  }
```

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

_{Reviews (1): Last reviewed commit: "fix: normalize MCP tool schemas missing ..." | Re-trigger Greptile}

Landed via temp rebase onto main.

• Gate: pnpm check && pnpm build && pnpm test && pnpm format
• Land commit: b69047d
• Merge commit: b4433a1

Thanks @yelog!

Related work from PRtags group unique-heron-2zsc

Title: Open PR duplicate: MCP schema properties + auto-reset override self-heal composite

* This PR