fix: Allow Agent to run with no tools

[sjrl]

Related Issues

• fixes Agent component has an Optional 'tools' init param, but fails if no tool is provided #9220

Proposed Changes:

Updates the init and run logic of Agent to truly allow Tools to be optional. This means an Agent can be run with no Tools now which makes it act like a normal ChatGenerator.

How did you test it?

Added a test

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 14472404591

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 11 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.003%) to 90.317%

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Files with Coverage Reduction	New Missed Lines	%
components/agents/agent.py	11	90.63%

Totals
Change from base Build 14471323317:	0.003%
Covered Lines:	10661
Relevant Lines:	11804

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💛 - Coveralls

[Amnah199]

Maybe we can update the Agent's docstring to also highlight this update.

[Amnah199]

LG! Just a small comment.

[LastRemote]

Sorry, one general question for the current behavior:

So the current tool_invoker would ignore the embedded tools inside of the chat generator? Not sure if this is intended but the chat generator might include some tools upon initialization (e.g. https://github.com/deepset-ai/haystack/blob/main/haystack/components/generators/chat/openai.py#L90). Not sure how we should handle this in the agent loop.

So even self.tools appear to be empty, there could still be tool_calls according to self.chat_generator.tools.

[sjrl]

Sorry, one general question for the current behavior:

So the current tool_invoker would ignore the embedded tools inside of the chat generator? Not sure if this is intended but the chat generator might include some tools upon initialization (e.g. https://github.com/deepset-ai/haystack/blob/main/haystack/components/generators/chat/openai.py#L90). Not sure how we should handle this in the agent loop.

So even self.tools appear to be empty, there could still be tool_calls according to self.chat_generator.tools.

Good catch. That is the intended behavior. The Agent component was set up in a way that the Tools should be provided to the Agent's init params and not the ChatGenerators.

But you're right we should make that more explicit that the tools defined in the underlying ChatGenerator will be ignored.

[sjrl]

@dfokina Could you give this docstring a review?

[dfokina]

I propose to order it a bit: "When you call an Agent without tools, it acts as a ChatGenerator, produces one response, then exits."