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

Annotations declare non-read-only, open-world, non-idempotent behavior, and the description adds substantial context beyond them: per-second pricing, plan/account requirements, the >45s latency expectation, the pending-then-poll lifecycle, and the host sign-in prompt. This is exactly the operational behavior an agent needs before invoking an expensive async generation.

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?

Four compact sentences, front-loaded with the core action and cost/latency caveats, with no filler. Slightly dense but every sentence carries information about cost, prerequisites, and the async lifecycle.

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 a 10-parameter schema with 90% coverage, an output schema, and rich annotations, the description supplies the remaining critical context: prerequisites, cost model, latency expectation, and the required get_job polling step. Nothing an agent needs to call this correctly is missing.

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 90%, so the schema already documents nearly every parameter (including the prompt/start_image exclusivity and duration constraints). The description only restates 'prompt and/or a start image' and adds no syntax or format detail beyond the schema, so the baseline 3 is appropriate.

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+resource ('Generate a short video') and the two input modes (prompt and/or start image), and names the sibling list_models as the source of model choices. It is clearly distinguishable from generate_image and other siblings.

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?

Explicitly routes the agent to list_models for model/tier selection, states prerequisites (needs a plan, requires a free StockCake account with a host sign-in prompt), and gives the follow-up pattern (expect a pending result and poll get_job). When-to-use is fully covered with no inference required.

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