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

Goes beyond the readOnly/idempotent/non-destructive/openWorld annotations by disclosing that Icypeas runs the search asynchronously server-side while this call blocks for the result — a genuinely useful behavioral fact not derivable from structured fields. It does not mention credit consumption or failure behavior when no email is found.

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?

Front-loaded with the core purpose, followed by the async/blocking nuance and one example; no filler sentences. The example is somewhat redundant with the schema example, keeping it from a 5.

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, yet the description never says what the result contains — whether it returns the email directly, a confidence/verification status, or a not-found indicator. For a lookup tool whose whole value is the returned email, that gap matters.

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 each parameter already carries its own description and an example object; the description's inline example largely duplicates the schema example. Baseline 3 is appropriate since the schema does the heavy lifting.

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 concrete verb+resource ('Find a work email') plus the exact inputs (first name, last name, company domain/name) and the provider. No sibling in the list performs email lookup, so the tool is unambiguous against the rest of the catalog.

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?

The required inputs imply the usage context (you have a name and a company/domain and want an email), but there is no explicit when-to-use/when-not or named alternative. With no competing sibling tool this is acceptable but adds no routing guidance.

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