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 x402 model at 0.002 USDC per call, that it reads Ethereum mainnet directly, and what data classes are returned. It omits error behavior (e.g., unresolvable names) and whether reverse results can be unverified, but core behavioral traits are covered.

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 tight sentences, front-loaded with the primary forward-resolution behavior, followed by reverse mode and then cost/source. Every clause carries information an 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?

No output schema exists, and the description names the returned fields (address, avatar, url, twitter records; verified primary name on reverse), which is adequate. It is slightly incomplete on failure modes and the exact response shape for partial records.

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 both parameters are already documented, including the dual ENS-name/0x-address use of 'name' and the 402 payment flow for paymentProof. The description adds only marginal value by restating the dual-input behavior; baseline 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 (ENS name) and covers both directions — ENS name to address/records and 0x address to primary ENS name. An agent can tell exactly what the tool does without opening the 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 makes the forward vs reverse selection condition explicit (ENS name vs 0x address), and no sibling tool performs ENS resolution, so differentiation is implicitly clear. It stops short of an explicit 'use this instead of dns_lookup' statement or exclusions.

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