petstore-api.getUserByName

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

Annotations declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, which the description does not contradict. However, the description adds no behavioral detail beyond the annotations, and critically, it fails to clarify how the 'user name' is provided given that the input schema is empty. This omission is a transparency gap that could cause invocation errors.

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 extremely concise, a single sentence with no fluff. It is structured logically (verb + object + scope). It earns a high conciseness score, though it could be enhanced with a covering sentence about input requirements without losing brevity.

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 empty input schema, the description is the sole source for inferring that a username is needed, but it doesn't state that this is a required parameter or how it should be supplied (e.g., as a path parameter). The tool name implies the input, but the description doesn't confirm or elaborate. With an output schema present, return values are covered, but the input side remains incomplete.

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 schema has zero parameters, the baseline is 4. The description adds the hint that the tool operates 'by user name', implying an input even though the schema lacks it. This is helpful but not fully explicit about parameter names or formats, so it doesn't exceed the baseline.

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 the action ('Get') and the resource ('user') with the scope 'by user name'. It distinguishes from sibling tools like updateUser and deleteUser, though it doesn't differentiate from the almost identical swagger-petstore--openapi-3.0.getUserByName. Overall, the purpose is 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 provides no guidance on when to use this tool versus alternatives such as getPetById or loginUser. It doesn't mention that it is a read-only lookup or that it requires authentication. There is no explicit when-not-to-use or alternative recommendation, leaving the agent without context for selection.

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