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

Beyond the readOnly/idempotent/closed-world annotations, it discloses that no sign-in is required, what each result contains (date, account count, exposed data types, summary, first steps), and the interpretation rules for match="similar" and no-match results. That is meaningful operational context annotations cannot carry.

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?

Densely packed but effectively front-loaded: the primary use case and example queries come first, then routing rules and caveats. Long and somewhat clause-heavy, yet nearly every sentence carries either a trigger, an alternative or a correctness caveat.

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 lookup with an output schema, the description supplies exactly the missing pieces: when to call it, what it returns in outline, how to interpret weak/no matches, and where to route instead. Nothing an agent needs to invoke it correctly is absent.

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% for the single query parameter, so the schema already defines format, length and the 'never an email/person/password' constraint. The description reinforces this with natural example phrasings but adds no new syntactic or semantic detail beyond the schema.

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 names a specific verb and resource — searches LeakData's public breach catalog by company, service or domain — and explicitly distinguishes itself from siblings (leakdata.search for email checks, leakdata.company_monitoring for one's own business). An agent can route to it without opening a schema.

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 gives concrete triggering utterances ('Was Canva hacked?'), names two alternatives with their selecting conditions, and covers exclusions ('Not for general security news or a person's name'). Edge-case routing is spelled out via emailCheckAvailable and the company-monitoring handoff.

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