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

Annotations only give readOnlyHint=false and openWorldHint=true, which are weak signals. The description adds critical non-obvious behavior: it starts a stateful handshake, emits a challenge, and imposes a hard 8-second time budget before the next call. That timing constraint is exactly the kind of operational detail annotations cannot express.

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?

Four short sentences, each carrying required information: purpose, precondition, return artifact, follow-up action plus deadline. Front-loaded and free of 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 zero-parameter handshake tool with no output schema, the description fully covers the workflow: when to call it, what it yields, and the exact next step with its deadline. Nothing an agent needs to complete the signup sequence is missing.

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?

Zero parameters, so baseline is 4. The description also explains that the challenge must be computed in code via pow(a, e, m), giving semantic context for the unknown a/e/m values that will likely be returned, rather than leaving them undefined.

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 action (start agent signup) and the concrete artifact returned (a modular-exponentiation challenge), distinguishing it from the sibling 'register' which it explicitly routes to. An agent can tell this is the first step of a multi-step signup 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?

Explicit sequencing: call this when you have no token yet, then call register within 8 seconds. Names the follow-up tool and the constraint that triggers it, leaving nothing to inference.

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