composite_preview

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

With no annotations, the description carries the full behavioral burden. It signals a non-final preview operation, but says nothing about whether it writes files, what format 'output' takes, or what permissions/alpha conventions are required. For a tool that takes an output path, that is a meaningful gap.

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 short sentences, front-loaded with the core action and immediately followed by the scoping caveat. Every word earns its place, with no filler.

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?

A 4-parameter tool with 0% schema coverage, no annotations, and no output schema leaves the description responsible for format, resolution defaults, and return behavior — none of which are covered. The definition is too thin for the tool's complexity.

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 0% across 4 parameters. The description only maps the foreground as an 'alpha foreground' composited over 'background', leaving output, height, and the expected file formats entirely unstated. It compensates only minimally for the zero-coverage 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+resource: preview an alpha foreground over a background. It also qualifies the intent ('checking edges, not the final comp'), which separates it from sibling compositing tools like chroma_key or matte_external. It stops short of naming a sibling explicitly, so it lands at 4 rather than 5.

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 phrase 'For checking edges, not the final comp' tells the agent both when to reach for it and, by exclusion, when it is the wrong tool. No alternative tool is named for producing the final comp, which keeps it below 5.

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