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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it is restricted to onchain resolvers, and off-chain CCIP-read names report resolved=false rather than erroring. Return-shape detail is still limited.

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 dense sentences, front-loaded with the primary purpose and followed by the key constraint. No filler, no redundancy.

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 carries return-value burden and does disclose the resolved=false outcome field. For a 2-parameter read tool with full annotation coverage, this is nearly complete, though it could spell out the remaining return fields (e.g. the resolved address/reverse name).

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%, so both parameters (name pattern/format and address reverse-lookup usage) are already documented in the schema, including the 'used if name is not set' precedence. The description restates the forward/reverse distinction without adding syntax or format detail beyond the schema, so 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), covering both forward resolution to an address and reverse-record lookup, and names the network (Ethereum mainnet registry). An agent can immediately tell this differs from dns_lookup/domain_rdap, which handle DNS and RDAP rather than ENS.

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?

Clearly frames the two operating modes (name set vs address set) and adds a coverage caveat that off-chain CCIP-read names return resolved=false, which steers the agent's expectations. It stops short of explicit when-not-to-use or naming an alternative tool, but there is no ENS sibling to route to.

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