### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

## Bug Report: `tool_choice.type: Field required` when using Claude via AWS Bedrock

### Description When asking a question through OpenKB chat using AWS Bedrock with the model `global.anthropic.claude-sonnet-4-6`, the system returns an error related to a missing `tool_choice.type` field.

### Error Message ``` [ERROR] litellm.BadRequestError: BedrockException - {"message":"The model returned the following errors: tool_choice.type: Field required"} ```

### Steps to Reproduce 1. Configure OpenKB to use AWS Bedrock with model `global.anthropic.claude-sonnet-4-6` 2. Open the chat interface 3. Ask any question 4. Error appears immediately

### What I've Tried - Setting `drop_params: true` in the LiteLLM configuration — error still occurs

### Expected Behavior The chat should respond normally without errors.

### Environment - Model: `global.anthropic.claude-sonnet-4-6` (via AWS Bedrock) - LLM proxy: LiteLLM - Interface: OpenKB chat

### Additional Context This may be related to how `tool_choice` is passed to the Bedrock API. The Bedrock API appea…