Cianplan

Level 5: AI / LLM systems · L5.5 Agents, tool use & MCP

Designing tools

Write tool interfaces an agent can use reliably.

12 min · Pro

What you take away

  • The tool definition is the prompt the model plans against, so most agent failures are fixed in the tool layer rather than in the system prompt or a bigger model.

And 3 more inside the class, in Pro.

How the class is laid out

  1. The problem
  2. The list of approved apps
  3. Five rules that fix most of it
  4. Check your understanding