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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the safety profile is covered. The description adds real value by disclosing the data sources (DNS MX/SPF lookups and Wikidata), which implies external calls and possible partial results, but it never says what happens for an unknown domain or whether missing fields are omitted.

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 with no filler, and the enumeration is genuinely informative rather than padding. It front-loads the returned contents rather than the action verb, which is a minor structural weakness but costs no clarity.

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?

With no output schema, the description carries the return-value burden and does so by listing the fields, including the non-obvious MX/SPF and Wikidata facts. It stops short of covering response shape, partial-data behavior, or error cases for unresolvable domains, which is the remaining gap.

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?

With one parameter at 100% schema coverage, the schema already documents 'domain' including the stripe.com example. The description only restates 'for a domain' and adds no format, normalization, or subdomain-handling 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 the exact resource and enumerates the returned fields (name, logo, social links, MX/SPF, Wikidata facts), which is more informative than a generic 'gets company data'. It implicitly distinguishes itself from siblings like company_logo and company_suggest by covering a bundle rather than a single field, though it never states that contrast explicitly.

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?

There is no when-to-use guidance, no prerequisites, and no mention of the obvious alternatives (company_logo for a logo only, company_suggest to resolve a domain first). The agent must infer the routing decision from the field list alone.

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