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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=false, idempotent=false) by disclosing that nothing is actually sent to WhatsApp, that output links expire after 1 hour, that the input is downloaded server-side into R2 only for the job's duration, and that processing runs via a headless browser. This data-retention and lifecycle detail is exactly what an agent needs before handing over a file.

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?

Purpose and the crucial 'does not send' correction are front-loaded, and the sentences are dense with real information. It runs slightly long, with infrastructure detail (ihateaudio.com tool page, headless browser on Cloudflare) that is not needed for selecting or invoking the tool.

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 still explains return values (download links that expire in 1 hour) and covers input requirements, optional format/bitrate controls, and file lifecycle. Nothing an agent needs to call this job-style tool 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%, so the schema already documents files, bitrateKbps and outputFormat. The description restates the input shape and adds a mild nuance ('where the tool supports them') about format/bitrate support varying, but adds no syntax or constraint detail beyond the schema — the correct baseline of 3.

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 outcome ('prepares audio to fit WhatsApp's 16 MB limit by recompressing it or splitting it at pauses') and immediately corrects the misleading name by asserting it 'does not send anything to WhatsApp'. That places it clearly apart from send_audio_by_email/send_audio_on_discord and from generic audio_compressor/audio_splitter siblings.

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 WhatsApp 16 MB constraint gives clear context for when to reach for this tool rather than a generic compressor. It does not, however, name explicit alternatives or state when-not to use it (e.g. for non-WhatsApp targets).

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