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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the safe read-only nature is covered. The description adds useful caveats by calling the scores 'subjective' and the phi score 'approximate', but it does not disclose additional behavioral details such as authorization handling, rate limits, or output variability. No contradiction exists.

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, well-structured sentence that front-loads the primary outputs and includes necessary qualifiers. Every word earns its place, and there is no repetitive or filler content.

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 output schema, rich input schema, and annotations, the description is largely complete for understanding the tool's core behavior. It could mention the optional measurement_key behavior or explicitly reference focused sibling alternatives, but those are already covered in structured fields, so the description does not leave major gaps.

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%, so the parameters are already fully documented with types, enums, and meanings. The description contributes little beyond stating that a single authorized adult photo is processed, which is consistent with the schema but does not add significant parameter-level insight.

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 what the tool does: it returns face-shape context, five subjective appearance scores, and an approximate Golden Ratio phi score for one authorized adult photo. This is a specific verb-plus-resource statement and naturally distinguishes score_face from the sibling tools that analyze a single facial attribute.

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 provides no guidance on when to use score_face versus the focused sibling tools, nor does it explain when to request the full report versus the optional measurement_key output. The intended usage is only implied by the tool name and the input schema, not by the description itself.

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