generate_thumbnail

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

No annotations provided, so description must carry full burden. It discloses the model (CodexImage), orientations, and text-free advice, but does not mention potential costs, idempotency, or how the generated thumbnail is stored/returned.

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?

Two concise sentences front-loading the purpose and key constraints. No wasted words.

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 no output schema and no annotations, the description covers core functionality but omits return value or integration details (e.g., how to retrieve the thumbnail). Adequate for a simple generation tool but not fully complete.

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 50% (only prompt described). The description adds relevant guidance for prompt (dramatic subject, strong lighting), but projectId lacks any elaboration in both schema and description.

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?

Clearly states it generates a text-free thumbnail via CodexImage with specified dimensions for landscape/shorts. Differentiates from siblings (create_project, generate_images, etc.) by targeting thumbnails specifically.

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?

Provides guidance on prompting (one dramatic subject, strong lighting) and advises adding text later, but does not explicitly state when to use this tool versus alternatives like generate_images or 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.