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

Annotations only declare readOnlyHint=false, idempotentHint=false, destructiveHint=false; the description goes well beyond them by disclosing the return contract (download links expiring after 1 hour), the processing pipeline (server download, Cloudflare R2 retention while the job runs, headless-browser processing), and data lifecycle ('The input is deleted when the job ends'). This is exactly the extra behavioral context annotations cannot carry.

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 purpose, then input, parameters, return contract, and lifecycle, so the agent can stop reading early. Slightly long at six sentences, and the Cloudflare/headless-browser infrastructure detail is more than an agent needs for selection, but nothing is redundant.

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 requirements and lifecycle. The only shortfall is the unresolved tension between the 'lossless FLAC' purpose and the lossy outputFormat examples, which could confuse format selection.

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 files/download_url/outputFormat/bitrateKbps are already documented structurally, establishing a baseline of 3. The description restates outputFormat and bitrateKbps with the qualifier 'where the tool supports them', adding only marginal meaning beyond the schema.

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+resource ('Converts audio to lossless FLAC') so an agent immediately knows the operation. However it never distinguishes itself from close siblings like audio_converter, mp3_converter, or wav_converter, and the stated purpose ('lossless FLAC') is muddied by an outputFormat that accepts mp3/m4a/ogg.

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 description gives an input precondition ('one file with a public HTTPS download_url'), which implies when it can be used, but offers no explicit when-to-use vs when-not guidance and does not route the agent to the other *_converter siblings for different target formats.

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