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

With no annotations, the description carries the full burden. It does add two genuinely useful facts absent from structured fields: the return shape ({ processedImage }) and the cost of 3 credits. It says nothing about permissions, processing latency, failure on non-face images, or whether results are stored in the artwork library.

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?

Three short sentences, front-loaded with the action, then the return value, then the cost. No filler and nothing an agent must skim past to find the essential facts.

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 two-parameter generation tool with full schema coverage, the description covers purpose, output shape, and credit cost, which is most of what a caller needs. The remaining gap is behavioral edge cases such as input rejection or async/sync behavior, which for a paid generation call would be worth one more sentence.

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 coverage is 100%, so both the image format (base64 data URI or HTTPS URL) and the style enum with its default are already fully documented. The description's "from a selfie" reinforces the image parameter but adds no new constraint or format detail.

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 pairs a specific verb ("Generate") with a specific output artifact ("a professional headshot") and names the input source ("a selfie"). It is clear enough to distinguish from avatar_generator or portrait_retouch by output type, though it never explicitly draws that contrast.

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?

There is no when-to-use or when-not-to-use guidance, and no sibling is named as an alternative. "From a selfie" weakly implies the input condition, but an agent choosing between headshot_generator, avatar_generator, portrait_retouch, and dslr_transform gets no routing help.

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