ctrl_add_list

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds context by explaining it's the standard way to layer noise, which is helpful. However, it does not describe what happens to existing controllers or whether the operation is reversible, though the annotation covers the destructive nature. The added context is useful but not extensive.

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 two bilingual sentences, front-loaded with the core purpose followed by a practical example. 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?

For a mutation tool with 4 fully documented parameters and no output schema, the description is sufficient. It explains the standard use case and ties to a related tool (constraint_set_weight), which helps the agent understand the workflow. It does not explicitly state that 'objects' defaults to selection, but that is in the schema, so the description does not need to repeat it.

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 100% of parameters with descriptions, so the baseline is 3. The description adds a specific example value for the 'layer' parameter (noise_position) and mentions weight tuning, which slightly enhances understanding beyond the schema. It does not, however, explain the exact syntax or interplay of parameters in detail.

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 'Add a List controller to a track' – a specific verb, resource, and operation. It also differentiates from the sibling tool ctrl_list by specifying that it adds (vs. lists) controllers, and the example with noise_position and constraint_set_weight distinguishes it from other ctrl_* tools that manipulate weights or list controllers.

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 a concrete use case: layering procedural noise on an existing animation, and explicitly references the companion tool constraint_set_weight for adjusting weight afterwards. While it does not explicitly say 'use this when...' or 'not for...', the example makes the intended usage clear and implies that weight tuning is done by a different tool.

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