Add Keyframe Animation to CapCut Draft

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

Annotations already indicate it's a non-read, non-destructive operation. The description discloses the core behavior (adding keyframes) and the return value (JSON confirmation), but does not explain potential side effects like how existing keyframes are merged, whether the draft must be saved afterward, or whether values are interpolated in a particular way. This adds some value but lacks rich behavioral context.

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 has a clear opening sentence and a helpful example, but the argument list duplicates almost verbatim the schema descriptions. This redundancy makes it longer than necessary. The structure is logical, but not every sentence earns its place given the schema already documents all parameters.

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 schema fully describes all parameters and annotations exist, the description provides enough to understand the tool's use: it targets an existing track, lists required arguments, includes an example, and states the return type. However, it does not cover the broader workflow (e.g., needing capcut_save_draft after adding keyframes) or the exact confirmation JSON structure. These are minor gaps, making it sufficiently complete for an agent.

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 description's argument list is largely redundant. However, the example ('property_types=['scale_x','scale_y'], times=[0,2], values=['1.0','1.5']') concretely ties the parameters together, showing how to specify a multi-property animation over time. This adds relational meaning 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 action ('Add property keyframes') and the target ('an existing track' in a CapCut draft). It lists specific properties (scale, position, rotation, opacity) and distinguishes itself from sibling tools that add new media or text, focusing on animation keyframing.

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 says 'to an existing track,' which implies the track must already have been created via other tools like capcut_add_video. It provides clear context for when to use this tool (animating existing content) but doesn't explicitly mention alternatives or when not to use it. The example illustrates a common use case (zoom-in).

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