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

Annotations already cover read-only/open-world/idempotency, and the description adds genuinely non-obvious context: live mainnet read, and a $0.002 USDC charge on Base via x402 billed 'per successful call'. That cost detail also explains why readOnlyHint is false (spending funds is a side effect) despite the tool being a read, resolving what would otherwise look like a mismatch.

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?

Four tight sentences: what it does, its two directions, the data source, then when to use it, then cost. The core capability is front-loaded and every sentence 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?

With no output schema, the description usefully names the return values it produces (wallet address, avatar, primary name) and discloses the payment model and data source. It is nearly complete for a one-parameter read tool; only failure/error behavior under x402 payment is left unstated.

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 description coverage is 100% and the single 'name' parameter already documents that it accepts either an ENS name or a 0x address for reverse lookup. The description restates the same dual-input semantics without adding format, normalization, or error-handling detail, so it is baseline-equivalent to the schema.

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 and resource (resolve an ENS name to address/avatar) plus the reverse direction (address to primary ENS name), and pins the data source as live Ethereum mainnet. An agent can distinguish this from generic siblings like 'domain', 'domain-report', or 'wallet' without opening a 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?

Gives two concrete use cases: turning a human-readable name into a payable address, and displaying a readable name for a counterparty address. Clear application context, but it names no exclusions or alternative sibling tools (e.g. when to prefer 'domain' instead), so it stops short of full routing guidance.

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