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

The description adds meaningful behavioral context beyond the sparse annotations by naming FFmpeg, H.264 re-encoding, and quality presets. It does not explain output-file handling or non-destructiveness, but the schema's file parameter already documents the returned MP4 format.

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 short sentence with the key behavior front-loaded. The 'Compress Video —' prefix and '[category: media]' tag are slightly redundant with the tool name and sibling context, but they add minimal overhead.

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 two-parameter tool with full schema coverage, the description plus schema is sufficient to select and invoke the tool correctly. Although there is no output schema, the file parameter description already specifies the H.264/AAC MP4 result, so the description does not need to repeat it.

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 100%, so the baseline is 3; the schema already explains the output format for 'file' and the CRF mapping for 'quality'. The description only repeats the high/medium/low preset names without adding new parameter meaning.

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-resource pair ('Compress Video') and explains the outcome (reduce file size) and method (H.264 re-encoding with FFmpeg). It is easy to tell apart from convert_video and media_trim_video, though it does not explicitly name an alternative.

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 phrase 'Reduce video file size' implies the obvious use case, but there is no explicit when-to-use/when-not-to-use guidance or mention of alternatives. In a large media/convert sibling set, an agent gets limited help choosing between this and convert_video or other compression tools.

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