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

Annotations declare readOnlyHint=true and openWorldHint=false, and the description is consistent with a safe read. It adds genuinely behavioral detail beyond the annotations — that values are verified onchain and that omitting chain switches to an all-chains listing mode. Return field names are given, though per-field formats and any caching/freshness behavior are not.

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, no filler. The returned-fields list comes first and the calling convention second, so the highest-value information 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?

With no output schema, the description compensates by enumerating the return fields, so an agent knows what it will get. For a one-optional-parameter read tool with annotations, nothing needed to call it correctly is 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 coverage is 100% with a single documented parameter, so the baseline is 3. The description adds the important semantic that the parameter is optional and that omission means 'list all chains', which the schema's description does not state, plus a second concrete example.

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 resource and enumerates exactly what is returned: contract address, decimals, EIP-712 domain (name, version, domainSeparator) and EIP-3009 support, plus the 'verified onchain' qualifier. An agent can tell instantly this is a metadata lookup, not an RPC call or payment tool.

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?

Explicit invocation guidance: accept a chain id (8453) or slug (base), and omit the parameter to list all chains. That covers the main decision the caller faces. No exclusions versus alternatives, though the sibling tools are unrelated so there is little to differentiate.

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