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

Adds value beyond annotations (which only declare openWorld, non-idempotent, non-destructive) by disclosing cost ('1 credit per image'), allowed output counts (1, 2 or 4), the reference-photo cap, and that results are asynchronous and must be retrieved via list_creations. Missing only latency expectations and failure/retry behavior.

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?

Front-loaded with the core purpose, then progressively adds constraints, cost and next step with no filler. The sentence fragments are dense to the point of being slightly clipped, but nothing is wasted.

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 an async generation tool with no output schema, the description supplies what matters: credit cost, batch size options, reference limits, and the exact follow-up call to retrieve results. A note on how long generation takes, or what the initial call returns, would close the remaining gap.

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 75%, and the description still adds meaning: reference photos are characterized by role (a face, a product, a style, a layout) and the 16:9 aspect is tied to the 'covers and YouTube thumbnails' use case. It does not retread the prompt-format guidance already in the schema.

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 and resource ('Images from your own prompt'), and crucially distinguishes itself from sibling generators via 'Not tied to the catalog' — separating it from generate_photos, generate_static_ads and remake_from_reference. The listed output types (covers, thumbnails, banners, posters) pin down the scope further.

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?

Gives concrete usage contexts (covers and YouTube thumbnails → use 16:9, banners, product scenes, posters) and an exclusion ('Not tied to the catalog'), plus the follow-up step 'Poll list_creations'. It stops short of naming the alternative tool an agent should pick when the image IS catalog-tied, so the routing is implied rather than explicit.

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