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

Annotations already declare read-only, idempotent, open-world and non-destructive, and the description goes well beyond them: it discloses the $0.01 price, the x402/MPP payment flow, that invalid input is rejected before any charge, and that an access key makes the tool pay and deduct automatically. That is substantial added context. The deduction is that the dual return modes (paid request object vs. actual data on the first daily call) are described in a way that is easy to miss, so an agent may misread what it receives.

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?

Purpose and checks are front-loaded, and the sibling redirect is placed well. However, the payment paragraph is dense and packs pricing, URL mechanics, key purchase URL, and the free-first-call exception into two long sentences, making the return-mode nuance hard to parse at a glance.

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 must carry return-value meaning, and it only partly does: it names the risk factors but never states the label's shape (categories, severity levels, accompanying evidence fields). Payment, idempotency, and error behavior are otherwise well covered for a tool of this complexity.

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% with an enum on chain and a regex on address, so the schema already carries parameter meaning and the baseline applies. The description adds only that input is validated before charging and that request_key is an idempotency key echoed back for retries, which is useful but marginal.

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 concrete verb and resource ("rule-based risk label on an ERC-20 token") and enumerates exactly what the label covers: sanctions lists (OFAC SDN, UK, EU), upgradeable proxy, and owner with mint/pause/blacklist powers. It explicitly separates itself from wallet_risk for non-contract addresses, so an agent can pick correctly without opening the 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?

Gives a decision point ("before you accept or route it") and names the alternative with its exclusion rule ("For a wallet (not a token contract) use wallet_risk"). It also documents the access-key path versus the unauthenticated path, which is the other branching decision an agent must make.

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