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

Annotations already indicate readOnlyHint, idempotentHint, and openWorldHint, so the description does not need to restate those. It adds valuable context beyond the annotations by disclosing the null return behavior for invalid slugs and listing the specific detail fields returned, which is helpful and non-obvious.

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 two sentences and immediately front-loads the purpose. Every clause earns its place: the slug source/example, the data returned, and the null behavior. No filler or 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?

Given the simple one-parameter schema, strong annotations, and an output schema, the description fully covers what the agent needs: when to call it, what input to pass, what it returns, and a failure mode. No meaningful gaps remain.

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?

Although the schema covers the slug parameter at 100%, the description adds crucial semantic detail: how to derive the slug from search_tools' toolUrl, including a concrete example ('/tools/acme-writer' -> 'acme-writer'). This goes well beyond the schema's generic 'The tool's listing slug.'

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 clearly states a specific verb ('Fetch') and resource ('full public detail for one AI tool by its listing slug'), and it distinguishes this tool from the sibling search_tools by defining the input as a slug from search_tools' toolUrl. The scope is precise and unambiguous.

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 instructs to call this tool after search_tools and explains what this tool provides that search_tools does not: full description, launch date, revenue signals, and for-sale status. This gives the agent a clear usage pattern and purpose relative to its sibling.

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