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

No annotations are supplied, so the description carries the full burden, and it does most of it: it discloses the return content (checksum form plus whether the input was already checksummed), the diagnostic meaning of a failure ('almost always mistyped'), and the cost model ($0.005/call over x402/USDC). It stops short of describing failure modes for malformed or non-EVM inputs, which would matter for an agent handling arbitrary strings.

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?

Four short sentences, ordered trigger first, then behavior, then rationale, then exclusions and price. No filler; every clause does work.

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 one-parameter pure validation with no output schema, the description supplies everything an agent needs: what is returned, how to interpret failure, when to choose a sibling, and the billing model. Nothing material 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% and the single parameter's 'in any case' semantics are already documented in the schema, so the description adds nothing beyond it. 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 and resource ('validates it and returns the EIP-55 mixed-case checksum form') and immediately names what it is not, routing the agent away from evm_is_contract and evm_ens by name. An agent can pick this over the ~60 siblings without opening a 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?

Explicit 'Use when an agent is handed an address and must decide whether it is safe to use before sending anything' plus two named exclusions with their alternative endpoints. Both the trigger and the carve-outs are spelled out, not implied.

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