Clarify distinction between script tools and retrieval tools in documentation

[n1colasf]

Description

This PR updates the documentation to clearly distinguish Script Tools from Retrieval Tools (Searches), so new users understand they are different concepts with different purposes.

It clarifies that:

• Script Tools are general Python capabilities for actions such as calculations, formatting, API calls, and orchestration.
• Retrieval Tools are searches specialized in semantic document retrieval through the Content API.
• Both can coexist in the same agent tools list, but they are used for different intents.

Type of Change

• Documentation update

Related Issues

Fixes #24

Changes Made

• Updated documentation in docs/index.md and docs/agents-tools.md to explicitly define Script Tools vs Retrieval Tools.
• Replaced ambiguous examples with concept-accurate examples:
  • Script Tool example now shows a real Python capability/action.
  • Retrieval Tool example stays focused on semantic document search.
• Added concise guidance that both types are configured in the same agent tools list, while serving different purposes (execute capabilities vs retrieve evidence).

Testing Done

• Tested manually

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• My changes generate no new warnings