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

With no annotations, the description carries the full burden and does well: it discloses the per-call cost ($0.02 USDC), the passive data source (CT logs, implying no active scanning), and the two-step payment flow where the tool returns x402 requirements and the agent's wallet settles them. It omits wallet prerequisites, rate limits, and failure modes, keeping it short of 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?

Every sentence earns its place: purpose, classification categories, cost, payment semantics, and a concrete call example. The most decision-relevant information (what it maps) is front-loaded with no filler.

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-value detail is not needed, yet the description still flags the unusual x402 payment-requirement return, which is essential for correct invocation. Only the input-format ambiguity and missing operational limits keep it below complete.

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 0% for the single 'domain' parameter, so the description must compensate. The inline example subdomains(domain="acme.com") clarifies the expected value format, but it never states whether a subdomain, URL scheme, or apex-only input is accepted.

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 ('Map') and resource ('a domain's live subdomain footprint'), names the data source (Certificate Transparency logs) and the output taxonomy, so an agent can distinguish this from sibling tools like dns, ssl_check, or headers without opening a 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 description never says when to reach for this tool versus alternatives such as dns or tech_stack, nor when it is inappropriate (e.g. apex resolution vs subdomain discovery). It supplies payment mechanics but no selection guidance at all.

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