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

With no annotations, the description carries the full burden, and it does disclose two real traits: the 0x-prefixed hex return format and the SHA3-256 fallback when ethers is unavailable. It says nothing about error behavior, input size limits, or what happens with empty input, so coverage is partial rather than complete.

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?

The purpose is front-loaded in a single tight clause, and the fallback note is a worthwhile addition. The trailing '🆓 5 free trial calls per signed wallet' is promotional filler that does not help an agent invoke the tool correctly.

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 no-annotation, no-output-schema tool with three undocumented parameters, the description does too little: it never resolves the parameter ambiguity and gives no return-shape detail beyond '0x-prefixed hex'. The fallback disclosure is the one genuinely useful piece of context.

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?

Three parameters (data, text, input) are present at 0% schema description coverage and the description only references 'text', leaving the role of 'data' and 'input' entirely unexplained – whether they are aliases, precedence-ordered, or distinct is unknowable. The description does not compensate for the severe coverage gap.

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+resource ('Returns the 0x-prefixed Keccak-256 hash of text as hex') and even adds the fallback algorithm, which separates it from generic hashing siblings like x402-hash. It does not, however, name any sibling explicitly, so differentiation still requires the agent to infer it.

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?

There is no when-to-use guidance: no mention of when Keccak-256 is preferable to x402-hash, x402-sha3, or the other hash tools in the sibling list. The only usage-adjacent text is the '5 free trial calls per signed wallet' pricing note, which is commercial, not operational guidance.

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