Place a rendered overlay on the timeline

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

With no annotations provided, the description carries the full burden and only reveals a prerequisite (CapCut closed) and the basic operation. It does not disclose side effects, error conditions, or whether the project is modified in-place, leaving notable gaps for a tool that alters a project file.

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 sentences with no wasted words, stating the purpose first and then a key prerequisite. It is highly front-loaded and easy to parse, earning every sentence's 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?

This tool modifies a CapCut project without annotations or an output schema, and the description omits important behavior such as how the project file is changed, failure modes, or handling of existing tracks. The prerequisite about CapCut being closed is useful but insufficient for safe operation given the tool's complexity.

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 60% of parameters (file, project, trackName), but the description adds no direct parameter explanations. The operation context implies startSeconds and durationSeconds refer to timeline placement, yet their units and behavioral meaning are not explicitly clarified, so the description only partially compensates for the undocumented parameters.

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 (adds), the object (an already-rendered clip), and the destination (a CapCut project on its own track). This distinguishes it from siblings like render_overlay or compose_overlay, which likely handle rendering or composition. The specific scope makes 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 usage for already-rendered clips and notes the prerequisite that CapCut must be closed, but it does not explicitly name alternatives or state when not to use this tool. It provides some context but lacks explicit exclusions or comparison to sibling tools, leaving the 'when vs alternatives' guidance implied rather than stated.

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