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

With no annotations, the description carries the full burden, and it does disclose a significant behavioral trait: the call costs 0.01 USDC via x402 or 12 sats via Cashu/Lightning, i.e. it is a paid, payment-gated operation. However, it says nothing about return shape, failure modes (NXDOMAIN, timeouts), or whether payment is required before or after resolution.

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, zero waste, and the core capability is front-loaded before the payment details. Every clause carries information the agent needs.

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?

For a simple one-parameter lookup with no output schema, the description covers the capability and the payment requirement, which is the non-obvious part. It is nearly complete; only the return format and error behavior are left implicit, which is minor for a tool of this complexity.

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?

There is a single required parameter at 100% schema description coverage, so the schema already documents the hostname and its example. The description adds no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 ("Resolve") and resource (A, AAAA, MX, TXT, NS, CNAME records for a hostname), which is unambiguous and immediately actionable. It does not explicitly distinguish itself from siblings like ipinfo or rdap, but the DNS-record scope is inherently distinct, so an agent can still route correctly.

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 gives no when-to-use guidance, no exclusions, and no alternatives among the many sibling tools (rdap, ipinfo, ssl, headers). It does disclose the per-call cost, which helps an agent weigh the call, but that is pricing rather than usage direction.

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