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

No annotations exist, so the description carries the full burden, and it does most of it: it discloses the OAuth requirement and the exact scope (profile:read), and lists the returned fields in lieu of a missing output schema. It does not state what happens when no profile is saved or when the token lacks the scope, which is the remaining gap.

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?

Two sentences, front-loaded with purpose and scope, then the auth prerequisite, then the usage rule. Every clause carries information an agent needs and nothing is repeated from structured fields.

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?

With no annotations and no output schema, the description compensates well by naming the fields returned and the auth scope. Only failure/empty-profile behavior is unaddressed, which is a minor omission for a zero-parameter read.

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?

Zero parameters, so there is nothing to disambiguate; the description correctly spends no words on inputs and instead describes the resource returned. Baseline 4 applies.

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?

States a specific verb+resource ('The signed-in user's saved Vitamin D profile') and enumerates exactly what is returned: skin type, exposed-skin default, age, target IU, current city. This clearly distinguishes it from update_my_profile, get_my_cities, and get_my_history.

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?

Explicitly says 'Call this FIRST for any personal question, then pass its values to the public tools instead of asking the user' – giving both ordering guidance and the alternative behavior (re-asking the user). No inference required.

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