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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), and the description adds genuinely non-obvious traits: which pages are scraped, that results are deduplicated, and that DNS records are included but mailbox verification is not. The billing model ('$0.01; nothing found is free') is valuable cost context an agent cannot get from structured fields; only rate limits and cross-page dedup rules are left unstated.

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?

A single dense sentence that front-loads the core purpose, then the output inventory, then the exclusion, then pricing. Every clause carries information; nothing is redundant with the title or schema.

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 read-only, two-parameter tool with an output schema, the description supplies the remaining decision-relevant facts: source pages, result types, what is deliberately excluded, and the cost/failure pricing. An agent has everything needed to decide to call it and to interpret an empty result.

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%, with both the required `domain` and optional `context` fully documented in the schema, so the baseline is 3. The description adds only a light gloss on `domain` (public company domain whose contact pages are inspected) and says nothing about `context` beyond what the schema already states.

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?

Names a specific verb and resource (published contacts for a company domain) and enumerates exactly what comes back: deduplicated emails, LinkedIn/X/GitHub links, and MX/SPF/DMARC checks. This clearly separates it from siblings like get_company_profile or private_blind_lookup without opening either 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?

States the intended input context (a public company domain's home/about/contact/team/careers pages) and explicitly excludes a neighbouring use case with 'not mailbox verification', which prevents the agent from expecting deliverability results. It stops short of naming an alternative tool for mailbox verification or for non-public contact discovery, so it is clear context rather than full when/when-not routing.

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