ENS / Basename expiry lookup (paid $0.001)

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 paid nature, the on-chain read via public RPC, the read-only characteristic, and the exact return fields (expiry date, days-left, grace period, release date, owner). It also explains the 402 challenge behavior. However, it does not mention error scenarios (e.g., invalid name) or rate limits, leaving some behavioral gaps.

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?

The description is concise and front-loaded, immediately stating the paid nature and the tool's function. Each sentence serves a purpose: payment info, what it resolves, what it returns, read-only status, and the argument/payment flow. No wasted words.

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?

Even without an output schema, the description lists the key returned data (expiry date, days-left, grace period, release date, owner) and explains the payment/challenge mechanism. It is reasonably complete for a lookup tool of moderate complexity, though it omits potential error conditions or formatting details. Siblings being unrelated means differentiation is not urgent.

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?

The input schema already provides 100% coverage with detailed descriptions for both parameters (name and x_payment). The description adds minimal extra meaning beyond restating the argument names and the payment flow, which the schema also explains. Thus, the schema carries the heavy lifting, so a baseline 3 is appropriate.

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 clearly states the tool resolves ENS .eth or Basename .base.eth registration expiry on-chain. It uses specific verbs ('Resolve', 'lookup') and names the resource ('registration expiry'), distinguishing it from sibling tools like gas, token_unlocks, and oracle_health, which address different domains.

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 provides clear context for usage: it is a paid read ($0.001 via x402), and explains the two-step flow (omit x_payment to get a challenge, supply it to settle and get the result). It does not explicitly discuss when not to use it or name alternative tools, but the context is sufficient given the unrelated siblings.

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