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

Beyond the annotations, it discloses that the user must open a link, sign in or sign up, upload a selfie, and that the call also runs the free photo check. It also explains that the returned connection_key must be kept for every account tool and never shown to the user, which is important behavioral context.

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 front-loaded with 'Start here to make photos' and then adds only necessary details about the link, sign-in flow, selfie upload, photo check, and connection_key handling. Every sentence contributes useful information without redundancy.

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?

Given the tool's complexity, lack of an output schema, and open-world behavior, the description covers the key return values, required user action, secret handling, and call frequency. An agent has enough context to invoke it correctly and guide the user.

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 has zero parameters, so there is no parameter semantics to explain. The baseline for a zero-parameter tool is 4, and the description appropriately focuses on outputs and usage rather than inventing parameter details.

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 states a specific onboarding action: it returns a link for the user to sign in or sign up, upload a selfie, and run the free photo check, plus a connection_key. It distinguishes itself from siblings by saying 'Start here to make photos' and that the key is needed for every account tool.

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?

It explicitly says to start here to make photos and to call it only once per conversation unless the key stops working. This gives clear when-to-use and when-not-to-use guidance without requiring inference.

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