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

Beyond the annotations, it discloses that live chain state may change between calls, that it does not simulate, send, sign, or assess safety, and that NOT_FOUND is a factual result. These details add meaningful behavioral context for an open-world read-only lookup.

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 description is front-loaded with the core purpose, then cleanly separates scope, usage conditions, exclusions, and error semantics. Despite its length, each sentence contributes useful selection or behavioral context.

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 only two fully documented parameters, existing annotations, and an output schema, the description supplies everything needed for correct selection and invocation. It also covers the key edge case of a valid but absent hash.

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 the input schema already documents the chain enum and the tx_hash pattern. The description reinforces that chain selects Ethereum or Base and that lookup is scoped to the selected network, but it does not add much parameter-level detail beyond the schema.

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?

The description states a specific verb and resource: look up an EVM transaction by hash and return normalized transaction facts. It explicitly distinguishes this tool from sibling decision, gas-price, balance, and latest-block tools by describing it as a factual post-transaction lookup and listing what it does not do.

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?

It provides explicit USE WHEN and DO NOT USE WHEN sections, naming the conditions that select this tool and the conditions that should route to alternatives. It also clarifies that a syntactically valid but missing hash returns NOT_FOUND rather than a validation error.

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