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

With readOnlyHint=false and openWorldHint=true already declared, the description goes further and explains the apparent anomaly: 'Reads or computes only; not marked read-only because each call is charged.' It also discloses the exact cost model ($0.003/call via x402 USDC or card key, first 25 free, failed calls free), which is pricing behavior no annotation conveys.

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 purpose before the usage note, example, and pricing, and every sentence carries information. The long field enumeration in the opening sentence is dense but earns its place given there is no output schema, though it could be tightened slightly.

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?

No output schema exists, so the description correctly carries the return-value burden by enumerating the fields returned. It also reconciles the annotations and discloses billing, leaving nothing an agent needs before calling it.

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?

Only one parameter, and schema coverage is 100% — the schema already specifies '0x followed by 64 hex characters'. The description's sample hash illustrates the format but adds no semantics beyond the schema, so the baseline of 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?

States a specific verb and resource ('Look up any transaction on Base by hash') and then enumerates exactly what is returned: status, sender/receiver, ETH value, method id, block, confirmations, gas, fee, contract creation. This distinguishes it from siblings like base_receipt or base_logs, which an agent can rule out without opening a schema.

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 confirm that a payment or contract call went through before acting on it' gives a clear decision context and a concrete trigger. It stops short of naming an alternative (e.g. base_receipt) or stating when this tool is the wrong choice, so it is clear but not fully routing.

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