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

Annotations declare readOnlyHint=false, openWorldHint=true, and non-idempotent, which for a pure lookup is counterintuitive; the description resolves this by disclosing the x402 payment model and the $0.003 USDC cost per successful call. That addition explains the surprising annotation. It omits rate limits/retry cost behavior, so it lands at 4 rather than 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?

Two sentences, front-loaded with the primary lookup then the return fields, followed by the usage cue and the cost. Despite the long field enumeration, every clause maps to a return value an agent needs, so nothing 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?

With no output schema, the description fully enumerates the return fields, plus usage guidance and the payment/auth requirement. An agent can call this correctly and interpret the result without further information.

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%: the hash parameter is fully specified in the schema (0x + 64 hex chars). The description only restates 'by hash' and adds no format or constraint 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?

Names a specific verb (look up) and resource (any transaction on Base) keyed by hash, and enumerates the full payload returned (status, sender/receiver, value, method id, block/time, confirmations, gas, fee, contract creation). It is clearly distinguishable from siblings like base_receipt, base_block, and the chain-prefixed *_tx tools.

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?

States a concrete when-to-use: 'confirm that a payment or contract call went through before acting on it.' That gives an agent clear trigger context. It stops short of naming alternatives (e.g., base_receipt for receipt-only data) or exclusions, so it doesn't reach a 5.

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