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

The annotations already declare read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower. The description adds useful auth context ('Needs no key') and clarifies that the OpenAPI document is returned, but it does not add much beyond that.

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?

It is a single efficient sentence with no wasted wording, and the key facts—API, OpenAPI document, plans, and no key required—are front-loaded. Slightly noun-heavy phrasing keeps it from being maximally clear.

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?

With an output schema present, no parameters, and strong read-only annotations, the description provides enough context to call the tool. It explains the returned resources and the no-key auth property; remaining details are covered structurally.

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 zero parameters, so the schema baseline is 4. The description does not need to explain parameter semantics and correctly focuses on what the tool returns.

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 names a specific resource set—the lookup API, its OpenAPI document, and the plans—and the title reinforces it as Nameclick's API/plans. It is distinguishable from the contact-oriented siblings, though it lacks an explicit verb like 'returns' or 'retrieves'.

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?

It gives clear usage context: 'for agents that call the API directly,' and adds the useful precondition 'Needs no key.' No exclusions or alternatives are needed because the sibling tools cover a different domain.

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