docs: Update toolset and searchable toolset docs

[sjrl]

Related Issues

• follow up to docs: Update tool docs #11236 and docs: Update component and pipeline tool docs #11237

Proposed Changes:

• Update toolset docs to use the recommended way to create tools (the tool decorator or the create_tool_from_function)
• Add package name like we did to components so its easier to know which library needs to be installed to use
• Added tips and notes to suggest to users preferred ways of creating tools and using tools.
• Updated example model in examples to gpt-5.4-nano instead of gpt-5-nano.

How did you test it?

Ran code blocks locally

Notes for the reviewer

The inspiration for this update was to help users and agents identify recommended patterns for tool use in Haystack.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have 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 have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

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Project	Deployment	Actions	Updated (UTC)
haystack-docs	Ready	Preview, Comment	May 4, 2026 0:30am

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.