get_user_by_id

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

With no annotations provided, the description carries the full burden of disclosing behavior. 'Look up' implies a read-only operation, but the description does not state what data is returned, how errors are handled (e.g., user not found), or any rate limits. This is insufficient for a tool with no annotation support.

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, concise sentence that directly states the purpose without unnecessary words or repetition. It is appropriately sized for a simple lookup operation.

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 (one parameter) and the presence of an output schema, the description is minimally adequate. However, it lacks any mention of when to use this tool over the sibling 'get_user' and does not describe expected return behavior, which would be important for an agent to select it correctly.

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 schema only lists 'user_id' as a string, and the description adds 'numeric user id', which clarifies that although the schema type is string, the value should be numeric. This is useful semantic information, but it does not explain the format, range, or any validation beyond type.

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 ('Look up') and the resource ('user profile') with a specific identifier ('numeric user id'). It is unambiguous about what the tool does, though it does not explicitly differentiate from the sibling 'get_user' tool, leaving mild ambiguity.

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 does not provide any guidance on when to use this tool versus alternatives like 'search_users' or 'get_user'. There is no mention of prerequisites, exclusions, or context where this tool is preferred, so the usage is only implicit.

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