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

Goes well beyond the annotations by disclosing the full job lifecycle: the server downloads the file, stores it in Cloudflare R2 while the job runs, processes it in a headless browser, and deletes the input when the job ends. It also states that returned download links expire after 1 hour, which an agent must know. This is rich context for a non-read-only job 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?

Front-loads the core operation in the first sentence, then covers input, settings, output, and lifecycle. Efficient overall, though the R2/headless-browser infrastructure sentence is heavier than strictly necessary for tool selection.

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?

With no output schema, the description correctly explains the return value (expiring download links) and covers input constraints, settings, and data handling. Minor gap: repeats/gapSec are named but their units/ranges are left implicit (gapSec implies seconds, repeats bounds unspecified).

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 100%, so baseline is 3, but the description adds meaning the schema lacks: it names the specific settings keys ('repeats, gapSec') even though the schema only declares settings as additionalProperties with a generic propertyNames, and it gives outputFormat examples plus a 'where the tool supports them' caveat for bitrateKbps.

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 ('Repeats a clip a set number of times, with an optional gap'), which is a unique operation not duplicated by any sibling. It does not explicitly differentiate itself from near-neighbors like audio_joiner or crossfade_joiner, so it falls just short of 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?

Usage is implied by the operation (loop a clip) and it states a real prerequisite ('one file with a public HTTPS download_url'), but there is no explicit when-to-use/when-not guidance and no alternative tool named despite a large sibling set.

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