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

Annotations already mark the tool read-only and idempotent; the description adds useful behavioral context: it is a free lookup requiring no key, and it explains the return shape (list of breach names or `breached=false`). This goes beyond the structured annotation fields.

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 compact: purpose first, then behavioral/output details, then routing to the alternate tool. Each sentence earns its place with no redundant 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?

Given the single parameter, rich annotations, and simple return semantics, the description covers everything needed to invoke the tool correctly. It states what the result looks likeasi and names the sibling for deeper investigation, leaving no critical 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?

The schema already fully describes the `email` parameter with 100% coverage)Skip, so the description adds little parameter-level meaning. It reinforces that the email address is the subject of the lookup, but does not introduce new constraints or formats.

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 precise action ('Check whether an email address appears in known data breaches') against a clear resource. It also differentiates itself from the sibling `email_breach_analytics` by noting that detailed per-breach information is a separate follow-up.

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?

It explicitly frames the tool for a simple breach-presence lookup and directs the agent to `email_breach_analytics` when more detail is needed. This gives clear when-to-use and when-to-alternative guidance.

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