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

Annotations already cover read-only and open-world behavior, but the description adds the critical operational trait that each call costs $0.003 USDC on Base via x402 — a fact an agent must know before invoking. It also discloses the fee breakdown (incl. L1 fee), though error/not-found behavior is unstated.

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 with zero filler: the first front-loads the full output payload, the second delivers the two decision-relevant facts (use case and price). Nothing is repeated from the schema or annotations.

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 correctly enumerates return fields and pairs that with the paid-call notice, making it callable without guesswork. Gaps are minor: no mention of behavior for unknown/unconfirmed hashes or chain mismatch beyond the schema's 'on Base' note.

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?

There is a single parameter with 100% schema description coverage ('0x-prefixed transaction hash on Base'), so the schema carries the semantics. The description adds nothing about the hash format or whether pending hashes are accepted, which is the correct baseline of 3.

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 ('Human-readable summary of a Base transaction') and enumerates the exact fields returned: status, block time, from/to, value, total fee incl. L1 fee, and decoded ERC-20 Transfer events. This clearly separates it from siblings like base_transfers, base_erc20_balance, and base_address.

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?

Provides a concrete use case — 'Handy to verify a payment landed' — which tells the agent when this tool is the right pick. It stops short of naming alternatives or exclusions (e.g. when to prefer base_transfers for a full history instead of a single tx lookup).

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