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

Annotations cover safety (readOnly, idempotent, openWorld), but the description adds substantial behavior beyond them: status tri-state (success/failed/pending), confirmations, decoded ERC-20 Transfer logs, and crucially the commercial model (x402 USDC on Base, $0.002 per successful call, PaymentRequired object on unpaid call) plus the 404-not-charged semantics. This is exactly the operational detail an agent needs and cannot get from structured fields.

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 trigger condition, then the return payload, then the pricing caveat — a sensible ordering. The middle sentence is long and heavily enumerated, but every clause carries distinct information (status, confirmations, decoded logs), so little is wasted.

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?

There is no output schema, so the description must carry the return contract, and it does: status, confirmations, timestamp, from/to, value, gas used and fee, method selector, contract created, and decoded Transfer logs. Combined with the payment and 404 behavior, an agent has everything needed to call and interpret this tool.

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 description coverage is 100% and both parameters are documented in the schema, including the chain enum and hash format. The description only restates 'Base or Ethereum', adding no format, default, or edge-case semantics 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?

Names a specific verb and resource ('fetches the transaction, its receipt and block from Base or Ethereum') and enumerates the decoded payload, so an agent can distinguish it from siblings like balances, holders or gas at a glance. The scope (single tx hash lookup, not a list) is unambiguous.

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 a clear triggering condition: 'Use when you need to confirm or explain a transaction (e.g. verify a payment arrived).' That is explicit context for invocation. It does not, however, name an alternative sibling or state when-not to use it, so it stops short of full routing guidance.

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