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

Annotations already cover the safety profile (readOnly, non-destructive, open-world), so the bar is lower. The description adds genuinely new behavioral context the annotations cannot carry: the per-call price (US$0.01) and a 3-free-calls-per-day quota, plus an explicit scope exclusion for personal data. It does not describe failure modes or latency, which keeps it at 4 rather than 5.

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?

Two sentences, front-loaded with what the tool returns and closed with the cost/quota and scope limits. Every clause carries information; nothing is repeated from 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?

An output schema exists, so return structure need not be explained, yet the description still summarizes the payload categories for selection purposes. Combined with the cost, quota, and scope-exclusion notes, an agent has everything needed to decide and invoke correctly.

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 at 100% schema description coverage, so the schema already carries the semantics ('domain', 'e.g. example.com'). The description restates 'from a domain' but adds no format, normalization, or subdomain/subpath guidance beyond the schema. Baseline 3 is correct here.

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 specific verb and resource ('Company profile from a domain') and then enumerates exactly what the profile contains: name, description, org facts, social pages, domain age/registrar, email/hosting providers, security basics. This is specific enough that no sibling (web_search, read_pages, get_reputation) could be confused with it.

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?

Gives a clear inclusion boundary ('Company facts only: no people, emails or phone numbers') and signals the batching rationale ('in one call'). It stops short of naming an alternative tool for when the domain approach is wrong, so it is clear context without explicit alternatives.

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