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

With no annotations, the description carries the burden. It discloses the OAuth scope requirement (profile:read) and notes the data is 'saved,' implying persistence. However, it does not mention potential errors, whether data is cached, or how authentication failure is handled. It adds useful context but leaves some behavioral gaps.

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 concise sentences. The first sentence immediately states what the tool returns; the second provides usage and authentication context. No filler, each sentence contributes meaningful information.

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 simple profile retrieval tool with no parameters and no output schema, the description covers the essential context: data contents, authentication requirement, and usage positioning. It doesn't mention return format or error behavior, but these are less critical given the simple nature and the presence of sibling tools for broader context.

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?

There are zero parameters, and the schema coverage is 100% (trivially). Per the rubric, 0 parameters earns a baseline of 4. The description adds no parameter-specific semantics because none exist, which is appropriate.

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 this tool retrieves the signed-in user's saved Vitamin D profile, enumerating specific fields (skin type, exposed-skin default, age, target IU, current city). It distinguishes itself from sibling tools by positioning it as the first call for personal questions, with values passed to public tools.

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?

Explicit guidance is given: 'Call this FIRST for any personal question, then pass its values to the public tools instead of asking the user.' This clearly indicates when to use and provides context for alternatives (public tools), though it does not name specific sibling tools or explicitly state when not to use it.

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