# \[Bug\] HTTP 400 after invalid browser\_tabs tool call

**URL:** <https://discuss.ai.google.dev/t/bug-http-400-after-invalid-browser-tabs-tool-call/177203>\
**Category:** Google Antigravity\
**Tags:** bug\
**Created:** [August 5, 2026, 3:26am UTC](https://discuss.ai.google.dev/t/bug-http-400-after-invalid-browser-tabs-tool-call/177203 "2026-08-05T03:26:29Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Lorddrust](https://d1dlmcr85iqnpo.cloudfront.net/user_avatar/discuss.ai.google.dev/lorddrust/32/32389_2.png) [@Lorddrust](https://discuss.ai.google.dev/u/Lorddrust)\
**Post date:** [August 5, 2026, 3:26am UTC](https://discuss.ai.google.dev/t/bug-http-400-after-invalid-browser-tabs-tool-call/177203/1 "2026-08-05T03:26:29Z")

</div>

## 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:

```auto
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:

```auto
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.

---

<div class="post-metadata">

**Author:** ![Lorddrust](https://d1dlmcr85iqnpo.cloudfront.net/user_avatar/discuss.ai.google.dev/lorddrust/32/32389_2.png) [@Lorddrust](https://discuss.ai.google.dev/u/Lorddrust)\
**Post date:** [August 5, 2026, 6:12am UTC](https://discuss.ai.google.dev/t/bug-http-400-after-invalid-browser-tabs-tool-call/177203/2 "2026-08-05T06:12:03Z")

</div>

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

Thanks.