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

Annotations already mark the operation as non-read-only and non-idempotent; the description adds that it sends an email and replaces the previous code. It also discloses the follow-up call to verify_email. No contradiction with annotations.

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, front-loaded with the primary action and followed by the required next step. No filler or repetition of schema details.

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?

The description covers the action, trigger, and next step, but it does not state where the new code comes from (response vs. user-provided), which the agent needs to actually call verify_email. With no output schema, this is a meaningful gap; otherwise the tool is simple and well-specified.

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?

The only parameter, token, is fully documented in the schema (100% coverage). The description adds no parameter-specific meaning, so the schema carries the burden; 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 action ('Send a new 6-digit verify code to the email already on file') and distinguishes it from verify_email by framing it as the step that precedes verification. The 'replacing an expired or lost one' clause clarifies the trigger condition.

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 identifies the use case: when a code is expired or lost. It also prescribes the next action ('Then call verify_email with the new code'), giving the agent a clear sequence. It does not enumerate exclusions or alternative tools, but the context is sufficient.

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