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

Annotations only indicate readOnlyHint=false and openWorldHint=true; the description adds the crucial asynchronous behavior, return of a generation_id, the polling pattern, and cost ('from $0.50'). These are valuable behavioral disclosures beyond the annotations, though it does not cover auth or rate limits, which are less critical here.

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 sentences with zero filler: the purpose is front-loaded, and the async flow and cost are stated efficiently. Every sentence earns its place, making it easy for an agent to parse quickly.

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 generation tool with 4 parameters and no output schema, the description fully explains the necessary calling pattern: initiate with text/image, receive a generation_id, and poll get_generation. It covers the core operational requirement (async polling) and cost, so an agent has everything needed to correctly invoke and follow up on this tool.

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 every parameter is documented in the schema. The description does not add extra semantic detail about parameters beyond what the schema provides, so the baseline of 3 is appropriate. It does not introduce any parameter-specific context that the schema lacks.

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 'Text and image to video', naming the specific resource and action. It distinguishes from sibling tools like text_to_video and image_to_video by indicating it handles both modalities in one tool, so an agent can tell them apart without inspecting schemas.

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 gives clear usage context: it runs asynchronously and instructs to poll get_generation until status is 'completed'. However, it does not explicitly mention alternatives (e.g., use text_to_video for text-only) or state when not to use it, so it lacks explicit exclusions but provides solid operational guidance.

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