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

With no annotations, the description carries the burden well: it discloses the payment model and cost ('$0.005 per call, paid over x402 (USDC)'), which is a real prerequisite an agent must know before calling. It also states the functional behavior (recover + compare). It stops short of saying what happens on a malformed signature (error vs. false), which is the main remaining gap.

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 sentences, front-loaded with the trigger condition, then the exclusions, then the cost. No sentence is redundant; even the pricing sentence carries decision-relevant information.

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?

No output schema and no annotations, so the description must explain returns — and it does ('recovers the address... says whether it matches'). All three params are schema-documented. The only omission is failure-mode behavior for an invalid or wrong-length signature.

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%, so baseline is 3; the description earns one above that by clarifying that the comparison against the expected address is the point of the tool and that the recovered signer is produced regardless, giving the optional 'expected' parameter meaning beyond its schema line.

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?

Specific verb and resource: 'recovers the address that signed a personal_sign (EIP-191) message and says whether it matches the one you expected.' It explicitly bounds itself against EIP-712 typed data and ERC-1271 contract signatures, which no sibling tool covers, so the agent can distinguish it immediately.

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 an explicit trigger ('use when an agent must decide whether whoever is talking to it really controls a wallet') and explicit exclusions ('Do not use for EIP-712 typed data or for a contract signature (ERC-1271)'). The when/when-not pair is unambiguous.

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