Summary

This PR updates the tool usage guidance in the system instructions and the agent tool description to provide clearer directions on when to use sub-agents versus direct tool calls.

GitHub Issue

N/A

What Changed

• Updated the instructions.ts file to refine the codebase exploration section, emphasizing the use of sub-agents for broad exploration (more than 3 files) and providing detailed guidance on how to use sub-agents effectively.
• Updated the agent.ts file to change the tool description for the 'agent' tool, mandating its use for tasks requiring reading more than 3 files or having multiple independent facets, and providing examples and clearer instructions.

Notes for Reviewers

None.