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

Annotations include idempotentHint=true and destructiveHint=false, which already indicate safety. The description adds valuable behavioral context: it warns against calling preemptively and explains that the upload widget will notify when the upload is complete. It doesn't disclose potential side effects such as storing the uploaded photo, but the idempotent hint covers repeat-call safety. No contradiction with annotations.

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?

The description is concise yet comprehensive, containing only four sentences. It front-loads the primary purpose, then immediately follows with explicit usage constraints and exclusions. Every sentence earns its place; there is no fluff or repetition.

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-parameter tool with a straightforward upload widget interaction, the description is complete: it explains when to call, when not to call, and what the widget does. It also indicates the notification behavior, which answers the likely 'what happens next' question. The sibling try_on context is included, making the decision path clear.

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?

The input schema has zero parameters, so the description carries no burden to explain parameters. The description's signal is that this is a no-parameter tool; however, it doesn't explicitly state that the tool requires no arguments, but that is already evident from the schema. The widget behavior is described enough to understand the upload flow.

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?

The description clearly states the tool's purpose: presenting an image upload widget for the user to share a selfie or photo for virtual try-on. The verb 'Present' is specific, and the resource is an upload widget, which is distinct from the sibling try_on tool. It also explicitly distinguishes when not to use it, reinforcing clarity.

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 provides explicit when-to-use guidance: call only after try_on returns a 'no selfie found' response or if the user explicitly asks to upload a new/different selfie. It also names the sibling tool 'try_on_product' and instructs not to call this tool if that tool already shows an onboarding/upload widget, preventing redundant calls. This is exemplary usage guidance.

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