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

Annotations (readOnlyHint=false, openWorldHint=true) already indicate side effects, but the description adds specific behavior: 'Sends a 6-digit code to the email' and 'Returns a verificationId.' This goes beyond the structured metadata, though it omits potential failure modes or timing details.

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?

The description is four sentences long, covering purpose, behavior, response, and usage trigger. Each sentence contributes value, but the list of examples ('past orders, reorder, saved address, email order-status') could be trimmed without losing meaning, making it slightly less concise than ideal.

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 2-parameter tool with no output schema, the description adequately covers the workflow: sends code, returns verificationId, instructs to call verify, and states when to use it. It does not mention token expiration, error handling, or rate limits, but these are not critical given the tool's simplicity.

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 100% with parameter descriptions for email and purpose. The description adds context by clarifying that email belongs to the customer and that purpose specifies the verification use case, but it does not significantly augment the schema, so 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?

The description states a specific verb and resource: 'Start email verification before showing a customer's private data...' It also differentiates from sibling vivid_identity_verify by explicitly saying 'Then ask the customer for the code and call vivid_identity_verify,' making the tool's role in the verification flow unmistakable.

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?

Provides explicit when-to-use guidance: 'Use this whenever a customer asks to see "my orders", "reorder", or "status by email" and you don't already have a valid identity token.' It also names the next step (vivid_identity_verify) and the condition for not using it, giving clear context versus alternatives.

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