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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the quota (3 free calls/day across all tools), the price and payment channel including the in-band params._meta["x402/payment"] key, and the data-source limits (company's own website and DNS only, robots.txt respected, no personal data). That is substantial operational context; only the failure/empty-result behavior is left implicit.

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?

One dense paragraph with no filler sentences, and each clause carries information. It is slightly mis-front-loaded, however: the billing/quota sentence leads ahead of the actual capability, which is the more important framing for tool selection.

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 need not be explained, yet the description's field list still frames expectations well. Combined with source restrictions, quota, and payment mechanics, nothing an agent needs in order to call this correctly is missing.

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?

The single parameter is fully documented in the schema, so the baseline is a 3-4. The description adds real value by documenting a parameter that is NOT in the schema at all: the x402/payment key passed under params._meta for paid calls, which an agent would otherwise not know to supply.

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?

"Company enrichment: domain in, company profile out" states a specific verb and resource, then enumerates the returned fields (name, description, language, logo, founding date, address, social profiles, key pages, MX). It also names the three sibling tools it is not, so an agent can route without opening any 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?

The "When to use" clause gives an explicit rule (enrich a domain) and pairs it with the exact alternatives: company-techstack for technologies, company-contacts for business contact details, company-batch for up to 10 domains. Both the selection condition and the exclusions are stated.

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