ENS name <-> address resolution

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint. The description adds the pricing ($0.002 per call) and the Ethereum mainnet scope, which are behavioral traits not covered by annotations. No contradictions.

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 sentences: first covers purpose and mutual exclusivity, second covers pricing. No filler, every word adds value. Front-loaded with the key action.

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?

The description is clear for a simple tool, but omits the return format (e.g., hex address string, null on failure) and error handling. Since there is no output schema, the agent is left to guess the result structure. Adequate but not fully complete.

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% with both parameters described. The description adds crucial semantics: 'Provide exactly one of name or address' (mutual exclusivity constraint not in schema) and provides an example value ('vitalik.eth') and clarifies 'EVM address' for reverse resolution. This adds significant meaning beyond 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?

The description states the tool resolves ENS names to addresses and reverse-resolves addresses to ENS names, explicitly mentioning Ethereum mainnet. It uses a specific verb (resolves) and resource (ENS name/address), and distinguishes between forward and reverse resolution. No sibling tool overlaps with this specific function.

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 guidance: 'Provide exactly one of name or address.' It also mentions the cost per call. However, it does not give explicit when-not-to-use instructions or compare with alternatives, though none are apparent among siblings.

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