combine_channels

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

No annotations are provided, so the description must carry the behavioral burden. It discloses the dimension precondition and the return value, but doesn't state whether the input views are modified or destroyed, or whether the operation is reversible. It implies creation of a new view (via 'renamed to'), but doesn't explicitly confirm the inputs are untouched. This is minimal but not misleading.

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 short sentences, front-loaded with the purpose, then the constraint, then the return value. There is no fluff or redundant information. Every sentence earns its place.

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?

Given the simplicity of the tool (4 required params, no output schema, no annotations), the description covers the essential points: purpose, constraint, and return. It doesn't mention error conditions or side effects, but those are implied by the dimension constraint. Compared to the calibration example for update_drive (which lacked permissions and reversibility), this is more complete because it gives the return and the key precondition. It's sufficient for an agent to call it correctly.

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?

The schema covers all parameters with descriptions (100% coverage), but the tool description adds a cross-parameter constraint: all three view IDs must have identical dimensions. This is not in the schema and adds meaning beyond what the schema provides. The description also clarifies the return value, which relates to the output_id parameter. So it adds value 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?

The description states a specific verb (Combine), the resource (3 mono views), the result (single RGB color image), and the method (ChannelCombination). It also names the return value. This clearly distinguishes it from siblings like lrgb_combine, which combines luminance with color, and create_luminance_mask, which does something different.

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 implies the tool is used when you have three mono views of identical dimensions and want to combine them into RGB. It doesn't explicitly mention alternatives or exclusions, but the purpose is clear enough that an agent would know when to select it. However, it doesn't say 'use this instead of lrgb_combine' or 'not for combining luminance', so it's not fully explicit.

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