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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: the auth prerequisite ('Needs a free SnoopScan key') and the shape of the results (contact form vendor, email provenance, social links). It doesn't mention rate limits or what happens on unreachable sites, but it clears the lowered bar set by 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?

Roughly four short lines, front-loaded with the purpose, then returns, then the auth requirement. No filler and no restatement of the title in prose form.

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?

An output schema exists, so return values are formally documented, and the description still summarizes them plus the API-key prerequisite. The main residual gap is how errors or sites without contact pages are handled, and slight redundancy with the output schema.

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?

One parameter, 'url', with 0% schema description coverage, so the schema carries no semantic detail. The description only implies the value is a company website URL ('for a company website'), adding no format, protocol, or scope guidance. Adequate but not compensating for the coverage gap.

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?

A specific verb+resource ('Find contact information for a company website') that an agent can distinguish from sibling tools like company, people, or findLeads. It also enumerates the returned artifacts (contact page, form + vendor, emails with provenance, social links). It stops short of explicitly naming which sibling to prefer, but the resource is narrow enough to be unambiguous.

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?

Usage is implied by the purpose rather than stated: there is no explicit 'use this when you need contact/enrichment data, use X instead' routing against siblings such as company or findLeads. The agent can infer the fit from the description, but no exclusions or alternatives are given.

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