render_video

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

With no annotations provided, the description carries the full behavioral disclosure burden. It does this well by specifying that draw(ctx, t, frame) must be deterministic, forbidding requestAnimationFrame and Date.now, noting optional setup(ctx) runs once, and stating the output is a file path plus sample frames. It does not cover render time, failure modes, or resource implications, leaving some behavioral gaps.

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?

Every sentence earns its place: purpose, function contract, optional setup, use cases, and return value. The most important constraint (pure deterministic draw function) is front-loaded, and there is no filler or repetition of schma details.

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?

The description gives an agent enough to call the tool correctly: the code contract, deterministic requirement, optional setup, and output shape. Minor gaps exist around duration_seconds semantics and more detailed return format, but the schema supplies defaults and the description covers the core complexity of code execution.

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 low, so the description compensates by adding crucial semantics for the required draw_code parameter: the draw function signature, time in seconds, purity requirement, and optional setup(ctx). It does not explain duration_seconds or the dimension/fps parameters, but these are self-explanatory and have defaults 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?

The description opens with a specific verb and resource: 'Render an MP4 from JavaScript canvas animation code you author.' It clearly differentiates from render_image (static image) and list_providers (provider listing), and reinforces the video/animation scope with 'Use for motion graphics, animated diagrams, explainers.'

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?

Clear use-case guidance is given ('Use for motion graphics, animated diagrams, explainers'), which implies when render_video is appropriate. However, it does not explicitly name alternative tools or state when not to use it, such as 'for static images use render_image instead.'

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