feat: Update search-actors tool

[jirispilka]

I really struggled to get GPT to work, so I ended up analyzing agentic prompts to better understand their tool instructions.

I had to update the system prompt so that GPTs would actually recognize that there are tools available to use.

You are a helpful assistant with a set of tools.

Follow these rules regarding tool calls:
1. ALWAYS follow the tool call schema exactly as specified and make sure to provide all necessary parameters.
2. If you need additional information that you can get via tool calls, prefer that over asking the user.
3. Only use the standard tool call format and the available tools.

Other changes:

• Changed tool description and arguments description
• Refactored evaluation

Important: For now, I have disabled LLM as judge. It was super misleading. I've documented everything in evals/README.md

[jirispilka]

Performance only on search-actors tools: tool exact match

[jirispilka]

Performance on the complete dataset (only tool exact mathc)

Before:

After