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

Annotations already cover readOnly, idempotent, non-destructive, openWorld, so the safety profile is done. The description adds genuinely new operational context: $0.04 per call over x402 on Base, a prepaid x-credit-token header for unlimited calls, no free tier, and no API key required. That pricing/auth disclosure is exactly the value-add expected when annotations are present.

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 purpose, then output contents, then payment terms. Em-dash-heavy but every clause carries information; the only mild redundancy is the explicit 'Required input: hash' which the schema already states.

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?

An output schema exists so return values needn't be explained, yet the description still previews the response (action, risk read, notes), and it fully covers the payment/auth path an agent needs before calling. Nothing critical is missing, though the lack of sibling disambiguation leaves a small gap.

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?

With one parameter at 100% schema description coverage, the schema already documents 'hash'. The description only restates 'Required input: hash' without adding format hints (length, 0x prefix, chain specificity). Baseline 3 applies when the schema does the heavy lifting.

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 ('explains what a Base transaction actually did in plain English') and enumerates the output shape: the action, a risk read, and notes. It implicitly separates itself from raw-decode siblings like tx_decode or base_receipt by emphasizing the plain-English interpretation, but it never names an alternative explicitly.

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?

The description tells you the required input ('hash') and the payment mechanics, but gives no guidance on when to reach for this versus tx_decode, receipt_parse, or base_tx. Usage is only implied by the 'plain-English' framing, so an agent must infer the boundary itself.

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