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

Annotations declare readOnlyHint=false, idempotentHint=false, openWorldHint=true, and destructiveHint=false, so the safety profile is mostly covered; the description adds meaningful context by disclosing the side effect (an email is sent to the inbox) and the downstream ownership consequence. It stops short of code expiry, resend/rate-limit behavior, or what happens on repeated calls, which is the remaining gap for a non-idempotent 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?

Three front-loaded sentences with zero filler: the ordering instruction comes first, followed by the action, then the exact next step. Every sentence earns its place.

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 one-parameter tool with no output schema and annotations already covering the safety profile, the description supplies enough to call it correctly and know what to do next. Missing only operational details like code lifetime or resend behavior, which are nice-to-have rather than blocking.

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 description coverage is 100% for the single parameter, and the schema already states the inbox receives the one-time code, so the description largely repeats it. It adds only the implicit constraint that the same email value must be reused in auth_verify_otp, which is marginal. Baseline 3 is appropriate.

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 — email a one-time sign-in code to a given inbox — and names its role in the flow, distinguishing it from the sibling auth_verify_otp that consumes the code. An agent can tell this tool apart from the rest of the auth family without opening the schema.

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?

Explicitly says to use it first, names the exact follow-up call (auth_verify_otp with the same email and code), and explains the ordering benefit (passport owned immediately, no separate claim step). Both when and what-comes-next are stated.

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