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

The description discloses the asynchronous job lifecycle: 'Returns a job_id immediately. Poll get_job_status until complete, then get_download_url.' It also explains side effects of each conform method, such as duration changes or audio time-stretching for speed_conform, and details error semantics and fallback behavior. This goes well beyond the sparse annotations and does not contradict them.

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 long but front-loaded with the core purpose and method breakdown. Each section—method options, duration_policy, job flow, reliability—earns its place. The reliability/fallback paragraph is somewhat tangential but still useful for an agent to avoid wasted work. It is structured enough to remain navigable despite its length.

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 complex tool with nested options, asynchronous behavior, and multiple conform methods, the description covers everything needed to call it correctly: inputs, method selection criteria, output handling, and failure recovery. The output schema exists, so return values need not be spelled out, and the description does not leave critical gaps.

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 75%, and the description adds meaningful semantics on top: what each method does behaviorally, why target_framerate is required, and the exact effect of duration_policy. It does not elaborate on width, height, bitrate, or output_format, but the schema already documents those clearly. The added value is concentrated on the most important parameters.

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 leads with a specific action and resource: 'Mux a separate video file and audio file (both public HTTPS URLs) into one fresh-encoded output.' It clearly identifies the conform step (combining and reconciling two sources) and differentiates from sibling tools like transcode/convert by requiring two distinct input URLs. The title and description together leave no doubt about what the tool does.

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 gives explicit selection guidance among the methods: 'use this when the rates already match' for mux, and concrete conditions for resample_video, interpolate_video, and speed_conform. It also explains duration_policy choices. It does not explicitly name sibling tools as alternatives (e.g., conform_media vs conform_from_url), but the two-URL requirement strongly implies the right use case.

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