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

The annotations already declare this a read-only, closed-world operation, so the bar is lower; the description still adds real context by declaring the call is free and that it returns a sale status with an offer link. It stops short of saying whether the free tier has quotas or whether the valuation is heuristic and therefore non-binding.

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, with the core purpose and the word 'Free' as the first two words, so the important part is front-loaded. The output enumeration in the middle is long, but because the tool has no output schema, each item still earns its place.

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 must make the return values clear, and it does so. A single required array parameter keeps the surface small, and the batch cap is disclosed. The only real omission is routing guidance relative to the sibling tools, which matters because their responsibilities overlap.

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?

Coverage is 100%, so 3 is the baseline; the description does better than that by disclosing the per-call batch limit of 100 names, which the schema does not encode as a maxItems constraint. The one gap is that it doesn't say whether the input is a bare domain or allows duplicates or a scheme.

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?

It states a specific verb and resource ('Free value estimate for any .ai domain name') and enumerates exactly what the agent gets back: auction, marketplace and brokerage values, ranges, name type, verdict and notes. It does not name or differentiate the sibling tools (get_domain, ai_domain_sales, search_domains), which is the only reason it falls short of a 5.

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 a clear implicit context (you want a valuation, not raw sales data) and a useful batch cap of 'up to 100 names per call', but the description never explicitly cross-references an alternative or a prerequisite, even when the sibling set is assumed to already exist.

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