add_image_overlay

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states what the tool does but not how the overlay behaves, whether the input video is modified or a new file is produced, how defaults like opacity/duration/scale apply, or what the output contains. This is a significant gap for a tool with nine parameters.

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 clean sentence with no filler, so it is concise in that sense. However, given the tool's complexity, it is under-specified rather than appropriately sized; it lacks the structural detail that would make it genuinely useful.

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?

Even though an output schema exists, the description is far from complete for a tool with nine parameters, two required inputs, no annotation guidance, and multiple similar siblings. An agent cannot correctly determine parameter semantics, expected outputs, or usage boundaries from this definition.

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%, and the description provides no parameter information at all. While property names like x, y, scale, opacity, and duration hint at their roles, the description does not clarify meanings, ranges, or relationships (e.g., what 'start' refers to, whether opacity is 0–1, or how output_path default works). The description must compensate for the uncovered schema, and it fails to do so.

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 verb and resource: 'Add an image on top of a video.' This clearly identifies the core operation. However, it does not differentiate the tool from nearby siblings like picture_in_picture or add_text, which could also serve overlay-like purposes.

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 about when to use this tool versus alternatives. With more than 40 sibling tools, including picture_in_picture and add_text, the agent is not told which tool is appropriate for which scenario. The description only implies the obvious use case without exclusions or prerequisites.

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