Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Describes the tool as 'Free' and action of returning recipients, but lacks details on side effects, rate limits, or authentication. Since annotations are absent, description partially covers behavioral traits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with purpose, and efficient use of words. Every sentence adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple parameterless tool with no output schema, the description provides sufficient context: what it does, that it's free, and how to use the output. Could mention return fields, but recipient_id is implied.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

No parameters, so schema coverage is 100%. Description doesn't need to add parameter info, and baseline is 4. No additional value needed.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states the tool returns saved recipients (address book). Differentiates from sibling tools like create_gift by indicating this is a data retrieval tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit guidance to reuse recipient_id in create_gift, implying the tool should be used before creating gifts. No need for alternatives since it's a simple list.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.