comp_add_overlay

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

With no annotations, the description carries the behavioral burden. It usefully discloses that overlay video is muted and its last frame is held, which is non-obvious and valuable. However, it does not cover image behavior, z-order, repositioning, or whether adding an overlay overwrites an existing one, so transparency is incomplete.

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 a single sentence with no filler. It front-loads the core action ('Add an image or video overlay') and immediately adds a high-value behavioral caveat, making every word earn 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 8 parameters, no annotations, no output schema, and zero schema description coverage, this brief description leaves too much unspecified. An agent cannot confidently know coordinate spaces, duration semantics, media source expectations, or what the function returns, so the overall context is incomplete.

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 description coverage is 0%, so the description must compensate, but it does not explain x, y, start, duration, width, height, comp_id, or media_id. It only hints that media_id should reference an image or video, and that duration relates to holding the last frame. Most parameter meanings remain inferred from names rather than documented.

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 action and resource: 'Add an image or video overlay', and adds a distinguishing behavioral trait ('overlay video is muted, last frame held'). This clearly separates it from siblings like comp_add_clip and comp_add_text, whose purposes are different even without reading their schemas.

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?

There is no guidance on when to use this tool versus alternatives such as comp_add_clip or comp_add_text. The description only states what the tool does, leaving the agent to infer selection criteria from the tool name and sibling list.

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