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

Goes well beyond the annotations, which only carry the generic readOnly/destructive/idempotent/openWorld flags. It discloses the full data lifecycle: the server downloads from download_url, stores the input in Cloudflare R2 for the duration of the job, processes it via a headless browser, deletes the input when the job ends, and returns download links that expire after 1 hour. That is exactly the kind of operational context an agent needs and cannot get from the schema.

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-loaded with the operation and the input constraint before the settings/format details and the storage/disposal notes. Six sentences is slightly long and the settings enumeration mildly duplicates the schema, but every sentence carries usable information rather than filler.

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 takes on the return-value burden and does so ('download links for the result, which expire after 1 hour'), and it covers the required input shape, optional knobs, and retention/cleanup. Nothing an agent needs to invoke it correctly is missing.

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%, and the description's parameter notes (settings keys intensity, speed, mix, decaySec; outputFormat examples; bitrateKbps) largely restate what the schema already documents, including the tool page that settings are passed to. It adds no syntax or value-range detail, so baseline 3 applies.

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 transformation ('slows a track down and adds reverb') and even names the composite edit it implements, which cleanly distinguishes it from the sibling single-effect tools reverb_adder and speed_changer without opening either 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?

Usage is implied by the phrase 'the slowed + reverb edit' and by the explicit input requirement (one file with a public HTTPS download_url), but the description never states when to pick this over speed_changer plus reverb_adder, nor any exclusions or prerequisites beyond the URL rule.

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