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

Annotations only declare the safety profile (readOnlyHint=false, destructiveHint=false); the description adds real behavioral detail beyond that: URL expiry (expiresInSeconds), size rejection via maxBytes, allowed mime types, and the required Content-Type match on the follow-up PUT. It even enumerates the returned fields despite no output 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 core purpose, then three numbered steps each occupying one sentence, closed by a terse return-field list. No filler sentences; every clause carries actionable information.

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?

Covers the full lifecycle: inputs, the out-of-band PUT, expiry/mime/size constraints, and the exact fields returned, all without an output schema. An agent has everything needed to complete the upload and hand off to speaker_separation.

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 the baseline is 3, but the description earns extra credit by tying mimeType to the downstream Content-Type header requirement and framing size as optional and validated against maxBytes, clarifying how each parameter participates in the workflow rather than just restating types.

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 ('mint a short-lived signed URL for uploading speaker-separation audio') and implicitly scopes it against siblings by routing the upload through speaker_separation. An agent can distinguish it from create_invoice_upload_url and get_file_download_url immediately.

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?

Gives an explicit three-step procedure with sequencing: call this tool, then HTTP PUT the bytes, then call speaker_separation with the returned path. It also states a negative constraint ('Do not POST the bytes to this tool'), which is exactly the when-not guidance agents need.

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