Apply a recipe

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

Annotations indicate readOnlyHint=false and destructiveHint=false, but the description adds critical behavioral context: the action 'takes effect immediately on the user's stream' and populates 'both canvases (H+V).' This reveals side effects beyond what annotations convey, making the tool's impact transparent.

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?

The description is three sentences, with the main purpose front-loaded. Every sentence adds necessary detail: the default behavior, the explicit usage condition, and the alternative mode. No wasted words or redundancy with schema.

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 tool has three parameters, no output schema, and minimal annotations. The description covers the key behavioral aspects: the two modes of operation, immediate effect on the stream, and the fact that both canvases are populated. This is sufficient for an agent to invoke the tool correctly in context.

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 descriptions cover 100% of parameters, so baseline is 3. The description adds value by explaining the relationship between recipe_id and target_scene_id: the default creates a new scene, while passing target_scene_id adds sources to an existing scene. This clarifies parameter interplay beyond the individual schema descriptions.

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 clearly states the tool's function: 'Apply a recipe to the live stream.' It further distinguishes its behavior from siblings by explaining the default action (creates a new scene and switches to it) and the alternative (adds to an existing scene via target_scene_id). This specific verb+resource+scope fully clarifies what the tool does.

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 gives an explicit usage directive: 'call only when the user asked to build/switch a scene.' It also explains when to use target_scene_id as an alternative to the default behavior. While it doesn't name sibling tools like create_scene, the guidance is clear and actionable.

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