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

With no annotations, the description carries the burden and does well: it discloses the return format (EIP-55 checksum) and the pricing/payment model ($0.005 per call over x402/USDC), which an agent cannot get from the schema. It stops short of stating error behavior for a failing checksum or any rate limits, so it is above baseline but not fully exhaustive.

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?

Three tight sentences: purpose first, the motivating use case second, and the cost detail last. Every sentence earns its place with no filler.

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?

For a single-parameter validation tool with no output schema, the description explains both the input expectation and the returned checksum form, and even surfaces the cost. Only the failure/error semantics for an invalid checksum remain 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 coverage is 100% and there is only one parameter, so the schema already documents 'address' including 'in any case'. The description adds only the EVM-type constraint (implied by the address format), which is marginal beyond the structured field.

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 (validates) and resource (EVM address) and even names the output form (EIP-55 mixed-case checksum). This clearly separates it from siblings like evm_ens, evm_is_contract, or util_keccak256 without needing to open any 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 a concrete usage context – run it before sending funds to catch typos. There is no explicit when-not or named alternative sibling, but the trigger condition is clear and actionable.

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