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

With no annotations present, the description carries the full behavioral burden, yet it only states the encoding method. It does not disclose whether the operation mutates or returns a new file, where the output is written, whether permissions or rate limits apply, or how the original is handled. For a media-transformation tool this is a substantial gap.

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?

A single tight sentence that front-loads the action and resource, with the codec detail appended. Every clause earns its place and nothing is wasted.

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 no annotations, so the description is responsible for explaining the return value, output destination, and behavioral constraints — none of which appear. With three parameters and a file-transformation side effect, an agent lacks enough information to call this confidently.

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%, with crf and fileUrl documented inline while resolution carries an enum and default but no description. The description's mention of 'CRF' loosely corresponds to the crf parameter but adds no syntax, range, or default guidance beyond the schema, so it neither compensates for nor worsens the partial coverage.

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 (compress) plus resource (MP4 video) and even names the codec method (H.264 CRF), which clearly separates it from siblings like compress_audio, compress_image, and compress_pdf. It does not explicitly mention an alternative by name, but the resource is unambiguous enough for an agent to select it.

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 description offers no when-to-use guidance, no exclusions, and no mention of alternatives such as convert_mp4_to_mp3 or the other compress_* siblings. Any routing insight must be inferred entirely from the resource name, which is the definition of implied-only usage.

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