[Bug] Tool invocation fails with string output interference

**Bug Description**
The tool call fails. Strings such as "course" appear in the output, the tool call fails, and the program stops running.

**Environment Info**
- Platform: darwin
- Terminal: Apple_Terminal
- Version: 2.1.161
- Feedback ID: 5adfb72d-c5c6-4326-a463-df741aa62fa8

**Errors**
```json
[]
```
