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

With no annotations, the description carries the full burden and adds important behavioral context: it is a paid lookup costing $0.01 USDC on Base via x402. It also discloses the malicious-address flag categories, though it does not explicitly state read-only behavior or rate limits.

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?

The description is a single front-loaded sentence with no wasted words. Capability and payment model are communicated efficiently.

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?

For a two-parameter lookup tool, it covers the core purpose and payment mechanism well. Since no output schema exists, a brief note on the returned fields or bidirectional behavior would improve completeness, but the essential information is present.

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%, so the baseline is 3. The description does not add meaning beyond the schema for either parameter: q is already described as an address or ENS name, and x402_payment is fully documented in the schema.

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 states a specific verb and resource: ENS-to-address (and reverse) resolution plus malicious-address flagging. It also names the flag categories (phishing, scam, sanctions, mixer), making its purpose distinguishable from siblings like token_risk or wallet_report.

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?

Usage is implied by the stated capabilities, but there is no explicit guidance on when to choose this over siblings such as token_risk or wallet_report. No exclusions or alternative-tool routing are provided.

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