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

With no annotations, the description carries the full burden, and it does disclose two useful traits: the trim is frame-accurate and the result is an MP4 (H.264/AAC) with an output_url. It says nothing about error conditions, whether start_s must precede end_s, bounds behavior when the range exceeds the video length, or any limits on source URL type.

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?

Three short sentences, front-loaded with the action and followed by parameter units and return format. Every sentence adds information and none repeats the schema verbatim.

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?

For a simple 3-parameter tool with no output schema, the description covers the operation, units, and the shape of the return value (MP4/H.264/AAC output_url), which is the main thing an agent would otherwise lack. The gap is the unexplained source 'url' parameter and unstated range/error behavior.

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, and it does clarify that start_s/end_s are seconds measured from the beginning of the video. However, the 'url' parameter receives no explanation at all (source video URL? supported formats?), leaving one of three parameters undocumented in both schema and prose.

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?

States a specific verb and resource ('Cut a clip out of a video') with the qualifier 'frame-accurate', which is enough to distinguish it from siblings like video_concat or video_convert. It does not explicitly name an alternative, so it stops short of a 5.

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?

Usage is implied by the verb 'cut a clip out of a video', so an agent can infer this is the tool for extracting a sub-range. There is no explicit when-to-use versus when-not guidance (e.g., versus video_convert or video_speed), and no prerequisites are stated.

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