Create keyer

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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses the full chain creation ('source (Select TOP or test card) → key stage → composite → Null TOP output'), the exposed controls on the container, and the return summary with 'node errors, warnings, and an inline preview image'. This is rich behavioral context beyond what annotations provide.

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 contributes distinct information: purpose, chain structure, mode comparisons, parameter roles, and return behavior. It is dense but not bloated, and it is front-loaded with the main verb and resource.

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?

With no output schema, the description compensates by explicitly detailing return values (container path, created node paths, exposed controls, errors, warnings, inline preview). It also covers optional inputs and the built output topology, making it complete for a complex creation 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 coverage is 100%, so the parameters are already described. The description adds workflow-level meaning, such as 'key_color sets the target colour to remove (chroma/rgb modes)' and the fallback test card when no source is given, which helps the agent understand parameter relationships and optional behaviors.

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 'Composite a keyed performer, logo, or any source over a background visual' and explicitly labels it as 'the green-screen / chroma-key / matte tool'. This is a specific verb+resource that distinguishes it from generic create_* tools, and it further details the three key_type modes to eliminate ambiguity.

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 provides context ('for installations and live camera work') and explains conditional behavior (with/without a source or background). However, it does not explicitly name alternatives or state when not to use this tool, though the context makes the intended use clear.

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