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

Annotations already declare readOnlyHint=true, so the read-only safety profile is covered. The description adds that this is a single-user lookup by ID and references the exact API endpoint, which is mildly useful, but it does not describe response shape, error cases, or any additional behavioral traits beyond what annotations already signal.

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 two short sentences with no filler. The core action and target are front-loaded, and the API endpoint reference is concise and useful.

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?

For a single-parameter, read-only GET operation with 100% schema coverage, the description plus annotations and schema provide everything an agent needs to invoke the tool correctly. No output schema exists, but return details are not necessary for correct invocation here.

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 100%, and the single parameter user_id is already described as 'The Vital user id (UUID).' The description repeats this concept ('by their Vital user_id') and adds the endpoint path variable, but it does not materially enrich the parameter semantics 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 states a specific verb ('Get'), a specific resource ('a single Vital user'), and the lookup key ('by their Vital user_id'). This clearly differentiates it from sibling tools like vital_list_users and vital_resolve_user without requiring the agent to infer scope.

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 implies usage: call this when you have a known Vital user_id and need that single user. However, it does not explicitly state when to prefer this over alternatives such as vital_list_users, vital_resolve_user, or vital_get_profile, nor does it give exclusions.

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