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

With no annotations, the description carries full burden for behavioral disclosure. It discloses that the tool runs on AI workers (Modal), credits vary by model/file size, Day Pass and welcome credits are excluded, files are deleted after processing, and tasks are auditable. This is rich, specific context beyond the basic function.

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 six sentences long, with several sentences about pricing plans and workspace unlock policies that are not strictly necessary for invocation. The core purpose is front-loaded, but the extra business context makes it less concise than ideal.

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 zero-parameter tool with no output schema, the description covers the key aspects: purpose, cost, file deletion, and audit trail. It omits the return format, but that is not critical given the tool's simplicity and the lack of structured output info.

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?

The input schema has 0 properties, so there are no parameters to describe. Schema coverage is trivially 100%, and the rubric sets a baseline of 4 for tools with no parameters. The description does not need to add parameter info, but it also doesn't compensate for any missing schema details.

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 'Generate professional headshots from any photo', which is a specific verb and resource. It distinguishes this tool from siblings like face_enhancer (which enhances existing faces) or image_generator (which creates new images).

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 (use this when you need a headshot from a photo) but does not explicitly compare to alternatives or state when not to use it. No mention of sibling tools or exclusions.

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