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

Annotations cover safety (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), and the description adds material traits the annotations cannot express: a 10-minute expiry window and per-email rate limiting. It also discloses the downstream authorization chain, which is exactly the behavioral context an agent needs before triggering an outbound email.

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?

Two sentences, zero filler, with the irreversible side effect (sending mail) and the critical constraints (10-minute expiry, rate limit) all front-loaded before any agent would need to page further.

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 output schema exists, and the description implicitly describes the side effect rather than the return value — it does not say whether the call returns a confirmation, an error on rate limit, or when the code may be resent. Given the simple single-parameter shape, the flow, expiry, and throttling coverage make it nearly complete, but the response/error behavior is the one remaining gap.

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?

Only one parameter with 100% schema description coverage, so the schema already carries the semantics ('the user's real inbox', maxLength 320). The description adds nothing about the parameter beyond 'the given email address', so the baseline 3 applies.

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 ('Sends a 6-digit verification code to the given email address') with the exact payload format, and explicitly distinguishes itself from the sibling verify_email_otp by assigning that tool the token-exchange role.

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?

Explains the workflow position clearly: this is step one, the code is exchanged via verify_email_otp, and the resulting token 'authorizes the draft tools' — that ties it to create_incorporation_draft and update_incorporation_draft. It stops short of stating when not to call it (e.g. if a token is already valid), so it is contextual rather than exhaustive.

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