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

With no annotations, the description carries the full burden and does so well: one-time use, 30-minute expiry, client-side processing (MediaPipe), and no upload. These are exactly the behavioral traits an agent needs to avoid misusing the tool or leaking data.

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?

Three short sentences, each load-bearing, with the core constraint and the lifecycle/expiry front-loaded and the follow-up action last.

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?

Despite having no annotations and no output schema, the description covers what is returned, its lifetime, where the check runs, the privacy posture, and how to retrieve the outcome — complete for a zero-param tool.

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 tool takes zero parameters, so per the rubric the baseline is 4. The description adds no parameter meaning, but none is needed.

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 ('returns a one-time 30-minute link') and clarifies the intended actor (your human, on a phone with a camera). It is instantly distinguishable from siblings like get_verification and get_verification_status.

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?

Sets the routing condition explicitly ('Bots cannot do the selfie check') and names the follow-up tool ('Poll get_verification_status for the result'), so an agent knows both when this applies and what to do next.

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