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

With no annotations, the description carries the full load and does disclose meaningful traits: the operation is paid ($0.002 USDC), the reverse lookup returns only a forward-verified primary name (a real correctness guarantee), and the two inputs are mutually exclusive. It omits failure behavior when both/neither parameters are supplied and any latency or caching notes.

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?

A single dense sentence covering both directions and returned fields, followed by the parameter rule and the price. Every clause earns its place and the core action is front-loaded.

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?

There is no output schema, and the description compensates by listing the record fields returned along with the primary-name verification semantics and the cost. For a two-parameter read tool this is nearly sufficient; only edge-case and error behavior are 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 description coverage is 0%, so the description must compensate; it does explain each parameter's direction (name resolves forward, address resolves in reverse) and their exclusivity. However it never specifies expected formats, e.g. whether "name" needs a .eth suffix or how the address should be formatted, which is a genuine ambiguity left open.

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+resource (resolve an ENS name / reverse-resolve an address) and enumerates the exact records returned (avatar, url, twitter, github, description). It is clearly distinguishable from siblings like block_lookup, token_metadata, and wallet_balances, which deal with different chain data.

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 a clear use condition for both directions and an explicit parameter-exclusion rule ("Pass name OR address"), which is the main routing decision an agent faces here. It does not name a sibling alternative or say what to do when neither is available, so it stops short of full when/when-not guidance.

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