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

Annotations already cover readOnlyHint/destructiveHint/openWorldHint, and the description adds genuinely new context: $0.003/call via x402 USDC or card key, first 25 free, failed calls free, and that repeats are charged. The billing detail also explains the non-obvious idempotentHint=false. The claim "reads or computes only and changes nothing" is largely redundant with readOnlyHint, which keeps it off 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 the action and the returned-field inventory, then the usage rule, then cost. Dense and free of filler. It runs long in a single sentence and the "reads or computes only and changes nothing" clause is padding against readOnlyHint, but nothing is structurally misplaced.

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 carries the full burden of describing the return payload, and it does so comprehensively (status, parties, value, method, block, confirmations, gas, fee, contract-creation flag). Pricing, auth path, and free-tier rules are all included, so an agent has everything needed to call and interpret this 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 description coverage is 100% on the single `hash` parameter, so the schema already states the 0x + 64 hex format. The description adds only a sample hash value, which is a small convenience but no semantics beyond what the schema documents. Baseline 3 is appropriate when the schema does the work.

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 opens with a specific verb+resource ("Look up any transaction on Base by hash") and then enumerates exactly what comes back — status, sender/receiver, ETH value, method id, block, confirmations, gas, fee, contract creation. That is far beyond a restatement of the name. It stops short of a 5 because it never distinguishes itself from the sibling base_receipt, whose field set overlaps heavily with what is listed here.

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 gives a concrete decision context: "Use to confirm that a payment or contract call went through before acting on it," which is a real when-to-use rule an agent can act on. It also states cost and free-tier conditions that affect whether to call. There are no exclusions, though — an agent choosing between base_tx and base_receipt gets no routing guidance.

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