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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact beyond the annotations: the returned URL expires after 15 minutes. It does not say whether the URL is single-use, whether calling it repeatedly creates orphaned URLs, or what auth the caller needs.

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 short sentences, front-loaded with the purpose and then the key return characteristic. No filler, no redundancy, and the expiry fact is placed where it is most useful.

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 one-parameter, low-complexity tool with an output schema, the description covers what the tool produces and its lifetime. However, it leaves the caller without guidance on how to use the URL (e.g., the upload method) or what to do after expiry, which matters for a widget-facing flow.

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?

There is one parameter, contentType, with 0% schema description coverage; only the enum values document it. The description never mentions contentType, so it contributes no meaning about why the type is required or how it constrains the upload. An agent must infer everything about the sole parameter from the enum alone.

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: creates an upload URL for a user-picked photo, in the context of the try-on widget. An agent can tell this is the pre-step to uploading a photo for virtual try-on. It does not name the sibling that consumes the URL (e.g., try_look_from_photo), so sibling differentiation is only implied by the flow.

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 phrase 'Used by the try-on widget' gives an implied usage context: call this when the user has selected a photo to try on. There is no explicit when-not guidance, no mention of which sibling to follow with, and no statement about prerequisites such as authentication or quota.

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