fix: change LlmAgent.tools to covariant Sequence

[jokester]

recreated from #1804 which got closed as "stale"

Fixes #1803

(the type mismatch still happens in google-adk v1.15.1)

[gemini-code-assist]

Summary of Changes

Hello @jokester, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a type mismatch issue within the LlmAgent class by refining the type annotation for its tools attribute. By changing the type hint from a concrete list to the more general Sequence, the change improves type compatibility and addresses a previously reported bug, enhancing the overall robustness of the google-adk library.

Highlights

• Type Hint Correction: The type hint for the tools attribute within the LlmAgent class has been updated from list[ToolUnion] to Sequence[ToolUnion].
• Issue Resolution: This change directly addresses and fixes a reported type mismatch issue (issue Agent() doesn't accept tools in list[FunctionTool] #1803) that was observed in google-adk v1.15.1.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request correctly addresses a typing issue by changing the type hint for LlmAgent.tools from list[ToolUnion] to Sequence[ToolUnion]. This change makes the type covariant, allowing for more flexible usage, such as assigning lists of tool subtypes without causing static analysis errors. The implementation is clean and effective. I have no further suggestions.

[adk-bot]

Response from ADK Triaging Agent

Hello @jokester, thank you for creating this PR!

Could you please include a testing plan section in your PR to talk about how you will test?

In addition, could you please provide logs or screenshot after the fix is applied?

This information will help reviewers to review your PR more efficiently. Thanks!