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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered; the description adds genuinely useful behavior beyond that: free-tier quota of 10 calls/day, the $0.001 overage, and the exact payment mechanisms (x402 via _meta or HTTP header, or X-API-Key credits). It also discloses that reverse lookups include forward verification, which matters for trusting the result. The only gap is behavior when neither name nor address is supplied.

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 tightly packed sentences, with the core capability front-loaded before the operational/payment details. No filler sentences, and every clause (records, L2, verification, pricing) carries information an agent or caller 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?

With an output schema present, the description needn't explain return values or pagination, and the cost/payment surface is fully spelled out. It falls short of complete only in not stating that at least one of name/address must be provided and how the two interact.

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% and each parameter already carries an examples-backed description, so the schema does the heavy lifting. The description restates record and L2 coverage but adds no syntax, format, or interaction rules (e.g., name and address being mutually exclusive or the accepted chains format).

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?

Names a specific verb (resolve) and resource (ENS name/address) and covers both directions plus the record fields returned (url/avatar/twitter/github) and optional L2. An agent can tell exactly what it produces, though it never contrasts itself with siblings such as ens_available or address_profile.

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 forward vs. reverse modes are apparent only from the parameter shapes and parenthetical hints ('or pass address'), not from explicit when-to-use statements. There is no guidance on which of name/address to supply, nor on when to prefer this over other ENS or address tools.

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