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

The description adds genuinely useful behavioral context that the annotations do not: cost ($0.001 USDC on Base per successful call) and the x402 payment mechanism, plus the fact that a nonexistent hash is a meaningful outcome. It does not, however, address the tension between its implied read-only lookup semantics and the annotations' readOnlyHint=false / idempotentHint=false, nor error behavior for malformed hashes.

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 the core action and scope, then the return fields, then usage and price in three compact sentences. The field enumeration is dense but earns its place given there is no output schema.

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, listing the returned fields is the right compensation, and the pricing/payment details cover the main hidden cost of invocation. It stops short of describing error/not-found handling or confirming that the hash must reference an Arbitrum One transaction.

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?

There is a single parameter ('hash') and schema description coverage is 100%, with the schema already stating '0x transaction hash'. The description says only 'by hash' and adds no format, chain-scoping, or validation detail beyond the schema, so the 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?

It names a specific verb/resource ('A transaction on Arbitrum One by hash') and enumerates the returned fields (sender, recipient, value, nonce, gas limit, selector, block), so an agent knows exactly what it retrieves. The chain qualifier separates it from eth_tx/base_tx/op_tx, but it never distinguishes itself from the closely related arb_receipt or arb_logs, so sibling differentiation is only partial.

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?

'Use to check what a transaction did or whether it exists' gives a clear use case and implicitly covers the not-found outcome. However, no alternative is named (arb_receipt for status/gas-used/logs, arb_logs for events) and there are no stated exclusions or prerequisites beyond payment.

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