Add Video Track to CapCut Draft

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

The description discloses that the tool modifies an existing draft and returns a confirmation JSON, which is useful. It also notes that video_url can be a local file path if supported by the backend. However, it doesn't mention side effects or failure modes beyond the schema, and the annotations already cover the non-read-only behavior.

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 structured with a clear opening sentence, an Args list, and a Returns line, making it easy to scan. It is somewhat repetitive of the schema but remains under control. The format helps the agent quickly locate parameter information.

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 description covers the core purpose, key parameters, and expected return value, which is important given the absence of an output schema. It also correctly notes the dependency on a draft created by capcut_create_draft. However, it lacks details on edge cases or advanced behaviors, but for a well-documented mutation tool this is adequate.

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 already provides full descriptions for all 11 parameters, including defaults and units. The description's Args list duplicates this information without adding new meaning, such as clarifying relationships between start/end or transform parameters. Since schema coverage is 100%, the description adds minimal value here.

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: adding a video clip to an existing draft's timeline, with specific use cases like background footage or B-roll. It distinguishes itself from sibling tools by explicitly targeting video clips, making the purpose unambiguous.

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 for video clips by providing examples, which helps decide when to use it. It does not explicitly contrast with sibling tools for other media types, but the context is clear enough. No exclusion criteria are given beyond the implied 'for video only'.

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