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

While annotations define the safety profile (read-only, idempotent), the description adds crucial behavioral context by defining how the count is calculated: it includes skills written specifically for the family AND skills written for any AI.

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?

The description is efficient and well-structured, addressing the core function, the filtering capabilities, and the counting methodology in a single, coherent statement.

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?

Given that all input parameters are documented and all safety behaviors are defined via annotations, the description is complete. It adequately explains the resource structure and the metrics returned by the tool.

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?

Since the input schema has zero parameters and 100% coverage, the baseline score is 4. The description does add marginal semantic value by listing the possible filtering dimensions (id, name, vendor), even if they aren't implemented as input parameters.

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?

The description explicitly identifies the resource ('AI model families') and the action ('Lists'). It clearly distinguishes this from the list of siblings by focusing on 'families' and defining the specific content of the listing.

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?

The description provides clear usage context by detailing the attributes by which the listed families can be filtered (id, name, vendor). However, it does not explicitly state when this tool should be used versus a similar tool like 'list_skills'.

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