Extract a local video frame

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

Annotations only declare the safety profile (readOnly=false, destructive=false, openWorld=false), while the description adds real behavioral context beyond them: it requires a local browser with native H.264 decoding, checks coded geometry before decoding, and verifies every PNG pixel. It omits what happens if output_path already exists, which is the main remaining gap for a write tool.

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?

Four sentences, each contributing scope, mechanism, exclusions, or prerequisites, with the core action front-loaded. It is dense and somewhat jargon-heavy ('admitted', 'coded geometry'), but no sentence is filler.

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?

There is no output schema, and the description covers the return implicitly by saying a new lossless PNG is saved and that audio, text, and metadata are excluded. Runtime prerequisites and path restrictions are stated, leaving only overwrite behavior unaddressed.

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 coverage is 67%, so most parameters carry their own documentation. The description adds meaningful semantics by specifying the frame is taken 'at or before' the requested time, but it does not explain time_seconds' 0-60 range or default value, which the schema only encodes numerically.

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: decode an H.264 source frame at/before a time and save it as a lossless PNG. The frame-extraction scope is clearly distinct from sibling video tools like abox_video_to_gif, abox_video_trim, and abox_video_rotate_bake.

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 use case (pull a still frame out of a video) is implied clearly, but there is no explicit when-to-use guidance or routing against alternatives such as abox_video_inspect or abox_video_rotate_bake. Usage is inferable rather than stated.

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