[Bug] HTTP 400 after invalid browser_tabs tool call

Google Antigravity
1

Summary

A normal chat request can finish its visible answer and then the trajectory aborts with HTTP 400 INVALID_ARGUMENT.

Steps to reproduce

  1. Start a new Antigravity chat.
  2. Ask in German: Welche Tools hast du?
  3. Antigravity lists its available tools.
  4. Seconds later the trajectory fails with HTTP 400.

Expected behavior

The assistant should finish normally, or invalid internal tool calls should be handled without terminating the trajectory.

Actual behavior

The local language-server log records an invalid internal browser tool call immediately before the 400:

error executing cascade step: CORTEX_STEP_TYPE_MCP_TOOL:
Invalid arguments for tool browser_tabs:
Invalid option: expected one of list|new|close|select

The trajectory then ends with:

agent executor error: INVALID_ARGUMENT (code 400):
Request contains an invalid argument.

Affected requests

  • Trajectory ID: 6e8312ba-648d-4973-8f6f-97279b…
    • Cloud AI Companion trace: 0x45eb5c2f2…
    • Error time: 2026-08-04 19:48:30 (Europe/Berlin)
  • Trajectory ID: d8577a14-12b4-4fc2-810f-3098…
    • Cloud AI Companion trace: 0x5bd4f72a…

Authentication had succeeded before the failure. This looks like an agent/tool-schema mismatch: the agent emits an unsupported browser_tabs action, and the backend subsequently returns a generic 400.

2

Update: The issue appears to be resolved now. The same workflow is working again without the HTTP 400 error.

Thanks.