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

Annotations declare readOnlyHint=false and destructiveHint=false, so the agent knows this mutates but is non-destructive. The description adds genuine context beyond that: the email-only channel restriction, the fact that a NEW code is generated and sent (invalidating the previous one by implication), and the auth prerequisite. It does not mention rate limits or whether prior codes are revoked.

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 short sentences front-load the action and the channel constraint, followed by a clearly separated ACCESS note. No 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 one-parameter, no-output-schema mutation tool, the definition covers the essentials and adds the non-obvious auth prerequisite. Remaining gaps (whether existing codes are invalidated, throttling behavior) are minor.

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% with a single 'id' parameter documented as 'Verification ID'. The description adds nothing about the parameter, 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 ('Resend a verification message') plus a channel-scoping constraint ('email channel only') and the side effect ('Generates and sends a new code'). It stops short of naming the closest siblings (resend_email_otp, resend_domain_email, trigger_verification), so differentiation still requires inference.

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?

The ACCESS block gives real operational guidance about prerequisite authentication and explicitly warns that start_login does NOT unlock this tool, which is useful. However, it offers no guidance on when to choose this tool over resend_email_otp, resend_domain_email, or trigger_verification for the same verification.

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