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

Annotations already declare readOnlyHint and openWorldHint, but the description adds two traits they do not cover: this is a paid call ($0.0004 via x402) and results are returned 'with evidence'. Pricing/payment model is exactly the kind of behavioral context annotations cannot express. It omits any error or rate-limit behavior, so not a 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?

One dense sentence covering the three data categories plus a short second sentence for the pricing. Front-loaded and essentially waste-free, though the parenthetical enumerations make it read as a run-on that takes effort to parse.

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 burden of describing returns, and it does so well by listing the specific fields each check produces. For a single-domain lookup the missing pieces (error cases, timing) are minor.

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 coverage is 100%, so the schema already documents both parameters and the baseline is 3. The description adds real meaning by spelling out what each 'checks' value yields — registration data, DNS records, and tech stack — which the enum alone does not convey.

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 a specific resource (a domain) and enumerates exactly what intel it produces across three dimensions (RDAP registration, DNS records, homepage tech stack). It is far more concrete than the sibling names alone, but it never explicitly positions itself against lookalikes such as site_audit, site_metadata, or resolve_name.

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 or when-not guidance and no mention of alternatives. The only hint of scope is the parenthetical 'unregistered = likely available', which implies a use case but does not tell the agent when to pick this over a sibling.

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