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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, but the description adds substantial operational context they do not carry: x402 payment on Base, $0.01 per call, prepaid x-credit-token header for unlimited use, one free call/day, and no API key required. Auth and cost details like this materially affect how an agent should invoke it.

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?

Purpose and the forward/reverse semantics are front-loaded, and the payment/auth tail is useful rather than filler. The pricing sentence is dense with clauses but each clause carries information, so it is efficient overall.

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 single-parameter resolver with an output schema (so return values need no explanation), the description covers purpose, direction, network, sibling differentiation, cost, and auth. Nothing needed to call it correctly is missing.

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% for the single 'query' parameter, which the schema already documents as 'ENS name or address'. The description reinforces that query is required and that it accepts either direction, adding light meaning but not detail the schema lacks.

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), resource (.eth names/addresses), direction (forward + reverse), and network (Ethereum mainnet), with a concrete example pair. It also distinguishes itself from the sibling basename resolver by naming the chain each covers.

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?

Clarifies the use context (forward to address, reverse to primary ENS name) and explicitly positions itself against basename as the Base counterpart. It does not state a when-not condition beyond that alternative, so it stops short of a full routing rule.

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