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

Annotations already declare readOnly, non-destructive, openWorld and non-idempotent, so the bar is lower; the description nonetheless adds real operational context: unknown hash returns 404 and is uncharged, failed calls are free, and repeat calls are charged because the operation is billed per call. It does not describe result formatting or latency, so it stops just short of a 5.

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?

Front-loaded with purpose and field list, then alternatives, input format, error behavior, price, and safety. Every sentence carries information, though the pricing/billing sentence is dense and slightly long-winded for what it adds.

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 listing the payload fields, and it covers input format, error semantics, billing, and safety for a single-parameter read tool. An agent has everything needed to call it and interpret a 404 correctly.

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 description largely repeats the schema's '0x-prefixed 64-hex hash' wording, which earns no credit. The concrete example hash is the one addition, giving the agent a valid sample value for the single required input.

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 ('Look up a HyperEVM transaction by hash') and enumerates the returned fields (sender, recipient, value in HYPE, nonce, gas limit, function selector, block). It explicitly separates itself from hyperevm_receipt and hyperevm_logs, so an agent can pick the right tool without opening 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 an explicit use case ('see what was sent or whether it exists') and routes the alternatives by purpose: hyperevm_receipt for success/failure and fees, hyperevm_logs for emitted events. The exclusion boundaries are stated rather than implied.

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