Compress a local H.264 video

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

Adds substantial context beyond the annotations: pre-decode header/slice validation, post-encode frame and timestamp verification, exact audio packet copying, and the important warning that the byte target is best-effort with possible size or color change. This tells an agent about failure modes and output fidelity that the flags alone cannot convey.

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?

Front-loaded action statement followed by verification, audio, and caveat sentences; every sentence carries information. The terse fragment 'Check fitted;' is awkward and slightly obscures the caveat.

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?

With no output schema, the description does not say what is returned on success or how a missed target is reported to the caller. Overwrite behavior for output_path and the meaning of max_side are also left unstated, which matters for a non-idempotent write tool.

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 only 40% (paths documented, but max_side, keep_audio, target_bytes undocumented). The description partially compensates by implying the byte target and conditional audio copying, but max_side, the 1920 default downscale, and the target_bytes range are never mentioned.

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?

Specific verb and resource: decodes an H.264 MP4/MOV locally and re-encodes to a new MP4 toward a byte target. This implicitly separates it from packet-copy siblings like abox_video_remux, but no sibling is named to make the boundary explicit.

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?

States a prerequisite (installed browser with native H.264 decode/encode) and a caveat (target may be missed), which implies the right context. However, it never says when to prefer remux/trim/join instead, and gives no guidance on what to do if exact size matters.

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