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

With no annotations, the description carries the full burden and delivers: it explains the email-verification handshake, that the agent never sees the link and must not ask for it, that client_name appears as an unverified claim, and the terminal 'denied' outcome. This is unusually rich behavioral disclosure for a write/identity tool.

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?

Front-loaded with the core action, then sequencing, then guardrails, with no filler sentences. It runs longer than most definitions, but each paragraph carries distinct operational content rather than restating the name.

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?

No annotations and no output schema, yet the description covers actor, side effects, the returned claim_token, the follow-up tool, and terminal states. Nothing an agent needs to invoke start_signup correctly 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?

Schema coverage is 0%, so the description must compensate, and it largely does: email is explained as the mailbox that receives the verification link, and client_name as the name shown to the user as an unverified claim. It never states that email is required or gives formatting constraints, leaving a small gap.

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: 'Create a Zeno account for somebody who does not have one yet.' It immediately distinguishes itself from request_api_key and collect_api_key by name, so an agent can route between the signup-flow siblings without opening schemas.

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 prerequisites and sequencing: use request_api_key first if the person might already have an account, then poll collect_api_key with the returned claim_token. It also states a hard stop condition ('denied is terminal ... do not start another'), which is exactly the when-not guidance an agent needs.

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