get_user

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

No annotations are present, so the description carries the full burden. The verb 'look up' implies a read-only operation, but the description does not explicitly state safety, rate limits, or error behavior. It is minimally transparent but not misleading.

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 a single, well-structured sentence that front-loads the main action. It is concise, with no wasted words or irrelevant details.

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 tool's simplicity, a one-line description is largely sufficient, and the output schema covers return values. The description adequately explains the input format, but lacks explicit mention of error handling or side-effect-free guarantees, which would be beneficial given the absence of annotations.

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?

The input schema only provides the parameter name and type with 0% coverage, so the description must compensate. The description clarifies that screen_name takes a @handle format with an example ('jack'), adding meaningful semantic meaning beyond the schema.

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 tool looks up a user profile by @handle (screen name), which is a specific verb+resource combination. It distinguishes itself from sibling tools like get_user_by_id (which uses an ID) and search_users, making the purpose 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 clear usage context by specifying the identifier type (@handle/screen name) with an example, implying this is the tool to use when you have a screen name rather than an ID. However, it does not explicitly mention when to use alternative tools like get_user_by_id, stopping short of a full when/when-not guidance.

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