## Description
---
1. This change introduces a userAgentRoundTripper that correctly
prepends our custom user agent to the existing User-Agent header
2. Moves sqladmin client to source.
3. Updated cloudsql tools for above support.
4. Add test cases to validate User agent.
## PR Checklist
---
> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:
- [x] Make sure you reviewed
[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a
[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
before writing your code! That way we can discuss the change, evaluate
designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [ ] Make sure to add `!` if this involve a breaking change
🛠️ Fixes #<issue_number_goes_here>
## Description
---
This pull request introduces the `cloud-sql-get-instances` tool, which
enables users to retrieve detailed information about a specified Cloud
SQL instance. This tool enhances the toolbox by providing a direct and
authenticated way to interact with the Google Cloud SQL Admin API.
Authentication is handled automatically by generating a bearer token
from the environment's Application Default Credentials with the
`https://www.googleapis.com/auth/sqlservice.admin` scope.
<img width="282" height="1064" alt="image"
src="https://github.com/user-attachments/assets/253d3939-7de2-4324-bc2b-8a2eb20eb133"
/>
####
## PR Checklist
---
> Thank you for opening a Pull Request! Before submitting your PR, there
are a
> few things you can do to make sure it goes smoothly:
- [x] Make sure you reviewed
[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a
[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
before writing your code! That way we can discuss the change, evaluate
designs, and agree on the general idea - Tracked internally
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
- [x] Appropriate docs were updated (if necessary)
- [ ] Make sure to add `!` if this involve a breaking change
🛠️ Fixes #<issue_number_goes_here>
