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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the safety profile is covered. However, the description adds no extra behavioral context and is actually misleading: it claims retrieval by 'internal id or Clerk id' while the schema accepts email and externalId as well, without clarifying which parameter maps to which id type. No information about error handling or multiple matches is provided.

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 with no filler. It is front-loaded with the purpose and easy to parse. However, it lacks structural elements like parameter guidance, but that is not required for conciseness.

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 and the presence of an output schema, the description still lacks crucial context: it does not state that at least one identifier is needed, nor how to choose among the three parameters. It also fails to clarify the meaning of 'internal id' and 'Clerk id' relative to the schema fields. The agent is left with insufficient information to call the tool correctly without inspecting the schema further.

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?

Schema description coverage is only 33% (only 'id' has a description). The description mentions two identifier types but does not map them to the actual parameters, and it omits email and externalId entirely. This leaves the agent uncertain about how to use each parameter, especially since none are required. The description adds minimal value and creates ambiguity.

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 states a specific verb ('returns') and resource ('a single user') and specifies identification by 'internal id or Clerk id'. It is clear about what the tool does, though it does not explicitly differentiate from sibling get tools beyond the resource type.

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?

No guidance is provided on when to use this tool versus alternatives, nor any exclusions. It does not mention that an identifier is required or what to do if multiple identifiers are provided. The description implies usage by id but gives no contextual direction.

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