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

Annotations already declare read-only and idempotent behavior, but the description adds substantive context beyond that: these lists are ordered by size, years in business, and completeness, not studio quality, and are not an endorsement. This prevents the agent from misinterpreting ranking semantics.

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 compact and front-loaded: it states the purpose and included fields first, then gives usage guidance and an important caveat. Every sentence adds value, with no redundancy.

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 zero-parameter read-only tool with an output schema, the description fully covers what the agent needs: what is returned, why the method matters, and when to call it relative to get_ranking. There is no obvious missing context.

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?

There are no parameters, so the schema covers everything vacuously and the description has nothing to add. The baseline of 4 applies because there is no param information to compensate for.

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 states a specific verb ('list'), a clear resource ('every ranked list the directory publishes'), and identifies the output fields (size, URL, slug, method). It also distinguishes itself from the sibling get_ranking by positioning this tool as the prerequisite lookup step.

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 explicitly says to use this tool 'to find the right list before calling get_ranking,' naming the downstream sibling and providing an actionable workflow instruction. It also instructs the agent to 'always pass the method on,' clarifying follow-up usage.

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