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

Annotations cover the safety profile (readOnlyHint=false, openWorldHint=true, non-idempotent, non-destructive), and the description adds real behavioral context beyond them: it sends a 6-digit code, returns a verificationId, and must be followed by vivid_identity_verify. It does not mention code expiry, resend behavior, or rate limits, which would round this out.

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?

Four compact sentences that are front-loaded with the purpose and the trigger, then the mechanics, then the next step. No filler, though the parenthetical intent list slightly overlaps with the final trigger sentence.

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 supplies the full operational story: prerequisite, side effect, return value (verificationId), and the downstream call. An agent has everything needed to invoke it and handle the result.

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%, so the baseline is 3, but the description adds meaning by mapping real customer intents (past orders, reorder, saved address, email order-status) onto the optional purpose values reorder | order_status | saved_details. The enum values themselves are not enumerated as a parameter contract, so it is useful but not exhaustive.

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+resource (start email verification) and immediately scopes it to gating private customer data, listing the concrete data categories it protects. It also implicitly differentiates from its sibling vivid_identity_verify by presenting itself as step one of a two-step flow.

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 states when to use it (customer asks for 'my orders', 'reorder', or 'status by email' and no valid identity token exists) and names the follow-up tool to call. The trigger phrases and the prerequisite condition leave nothing to inference.

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