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

With no annotations, the description carries the full burden and does well: it discloses billing rate, asynchronous job semantics with a named polling tool, and a 1-hour expiry window for output links. It still omits whether the source video is modified or preserved, which is the main unresolved behavioral question for a transform 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 front-loaded sentences: purpose first, then cost, async handling, and expiry. The long enumeration in sentence one is dense but scannable; nothing is redundant or 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?

For a 13-parameter, no-annotation, no-output-schema tool, the description covers the critical gaps: how long-running work is retrieved and how long links live. It is nearly complete, missing only an explicit statement about what the call returns and whether the input asset is left untouched.

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 already 100%, so the baseline is 3, but the description adds genuine meaning: the aspect_ratio use case (9:16 for Shorts/Reels), the crop-to-fill vs pad-with-bars choice corresponding to the fit enum, and the note that speed changes preserve audio pitch. These go beyond the schema text and justify a 4.

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 opens with a specific verb+resource and enumerates concrete operations (aspect ratio, downscale, rotate, flip, speed, frame rate, mute), so an agent knows exactly what the tool transforms. It does not, however, differentiate itself from overlapping siblings like compress_media (downscaling) or convert_media (format), which is why it falls short of a 5.

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?

It gives clear operational context: cost is 1 credit per minute of output, long jobs return a job_id that must be polled with get_job, and result links expire in 1 hour. What's missing is any explicit when-not/to-use-alternative guidance versus trim_media, convert_media, or compress_media.

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