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

Annotations already declare readOnlyHint/idempotent/non-destructive, so the safety profile is covered; the description reinforces this ('never starts or changes a run') and adds genuinely new behavioral detail about what state is reported (which of the 7 steps are done, the script) and when the MP4 URL becomes available. It stops short of describing polling/rate behavior or how partial runs are represented.

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 dense sentence with the core action front-loaded and the read-only caveat last, which is the right ordering. The parenthetical about the 7 steps adds precision rather than padding, though the sentence is long enough that it could be split for scannability.

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?

Given an output schema exists, the description needn't enumerate return fields, yet it helpfully sketches the important ones. The only real gap is the absence of polling guidance for a progress-check tool, which is the main thing an agent needs to use it correctly over time.

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?

One parameter with 0% schema description coverage, so the description carries the burden, and it only implies that project_id identifies the run within 'the user's ManyMotions account'. It adds no format, provenance, or where-to-obtain guidance for project_id. Adequate but thin for the sole input.

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?

States a specific verb and resource ('Check the progress of a video run'), names the concrete return ('the finished MP4 URL when the final cut is ready'), and the read-only clause implicitly separates it from generate_video, which starts a run. An agent can route between this and its siblings without opening a schema.

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?

Clear context for use: polling progress of an existing run and retrieving the output URL. The line 'it never starts or changes a run' implies generate_video is the tool for starting one, but no alternative is named explicitly and no precondition (e.g. an existing project_id from a prior run) is stated.

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