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

Annotations already declare readOnly, idempotent, openWorld and non-destructive behavior, so the safety profile is covered. The description adds real value beyond that: it discloses that the tool returns an address only when Prospeo reveals AND verifies it, and that masked/unrevealed guesses surface as "not found" rather than a bogus address — a behavioral trait not derivable from the 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 tight sentences plus one worked example, with the core capability front-loaded and the return-behavior caveat following. No filler and nothing redundant.

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?

There is no output schema, so the description must carry return semantics — and it does, explaining that the result is either a verified email or a not-found signal. Adding failure/auth facets (e.g. invalid key or rate limits) would make it fully complete, but it covers what an agent needs to call it correctly.

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%, so every parameter (including the optional company_name and _apiKey) is already documented with examples in the schema. The description adds the required-parameter framing but no syntax or format detail beyond what the schema provides, so the baseline of 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 precise verb and resource ("Find a person's verified work email") plus the exact inputs that produce it (first name, last name, company domain), so an agent knows immediately what the tool produces and how to constrain it. It is unambiguous and self-distinguishing from the unrelated siblings in the toolset.

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?

Gives clear context ("Prospeo's person-enrichment API", person+domain lookup) that tells the agent when this tool applies. It offers no explicit when-not guidance or named alternative, but the siblings are unrelated domains, so no exclusion is genuinely needed.

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