Key points
- Giving an agent many tools (18 rather than 4 or 5) degrades selection reliability.
- Agents with tools outside their specialisation tend to misuse them (a synthesis agent running searches).
- Scoped access: only the tools needed for the role, plus limited cross-role tools for high-frequency needs.
- tool_choice options: auto (text or tool), any (must call some tool), forced selection of a named tool.
- Generic tools can be replaced with constrained ones, such as load_document that validates URLs instead of fetch_url.
Common misconceptions
- "More tools make an agent more capable." Past a handful, they make it less reliable.
- "any forces a particular tool." It only forces some tool call.
- "A prompt rule stops an agent misusing an available tool." Removing the tool is what guarantees it.
Watch for
Agents handed every tool "just in case", and mandatory first steps left to the prompt instead of forced selection.
Practice Task 2.3
Start with the free 10-question check to see where you stand across all five domains. In CCA Prep Studio, 57 practice items cover this task, each tracked toward your mastery score.