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

With no annotations, the description carries the full behavioral burden and does well: it discloses credit cost and runtime per model tier, the 5-second default duration, and the timeout/save-recovery path via get_render_status. It does not describe authentication requirements or the exact shape of the returned asset beyond 'saved video asset'.

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-loads the core action, then packs model tradeoffs, default duration, failure recovery, and the prompt prerequisite into tight clauses with no filler. Every sentence carries actionable information for invocation.

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 six-parameter generation tool with no output schema, the description covers the key caller concerns: cost, latency, defaults, prerequisite prompt enhancement, and timeout recovery. It could add a bit more on the returned asset or where the video is stored, but nothing critical for correct invocation 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 coverage is 100%, so the baseline is 3, but the description adds genuine meaning beyond the schema by attaching cost (10/25/30 credits) and latency (~30s, 1-2min, 2-3min) to each model enum value, plus confirming the 5-second default duration. The resolution and title parameters receive no extra semantic detail beyond 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 ('Generate a video from a still image using AI'), which clearly separates it from siblings like generate_image, stitch_video, and scrape_video. An agent can identify the tool's function from the first sentence alone.

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 alternatives under named conditions: use enhance_prompt first if the prompt is generic, and use get_render_status if the tool times out. It also guides model selection by cost and latency, giving concrete when-to-use criteria rather than leaving them to inference.

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