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

Annotations only flag destructiveHint=true and idempotentHint=false; the description goes well beyond by disclosing the exact timing semantics — the existence check happens once at mint time and the URL can still overwrite a key created afterward. That TOCTOU nuance is exactly the behavior an agent cannot infer from structured fields and materially affects correct use.

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?

Two tight sentences plus a clarifying clause; the core artifact is front-loaded and every sentence carries non-redundant information about overwrite timing. No 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?

For a no-output-schema tool, the description covers the essential semantics, but it never states what the call actually returns (the signed URL and its effective expiry). The schema's expiresInMinutes text hints at this, yet with no output schema the return shape remains implicit.

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 real meaning to `overwrite` by explaining that the check is evaluated once at mint time rather than at upload time. The `expiresInMinutes` clamping/reporting behavior is left entirely to the schema, so it does not fully rise to 5.

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 — minting a short-lived pre-signed PUT URL for direct upload — which is immediately distinguishable from create_download_link and the multipart/upload siblings. The 'PUT URL' detail and 'uploading content directly' phrase tell an agent exactly what artifact it gets.

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 supplies a precondition for the overwrite path ('refuses to mint the link if the key already exists unless overwrite is true'), which is useful usage context. However, it never says when to prefer this over write_object, start_multipart_upload, or presign_upload_parts, so the routing decision is left to inference.

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