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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description goes well beyond them: it discloses the paid x402 model, the exact cost ($0.125 per call), the endpoint, that the tool returns a ready-to-POST request rather than the data itself, and that bad input is refused before any charge. Those are behavioral traits an agent cannot get from annotations or schema.

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 use condition and scope, then the mechanics; nearly every clause carries information. It is dense and packs payment and endpoint detail into one long sentence, which costs a little readability but not waste.

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, but the description explains that the return value is the exact paid x402 request body plus a response schema and example, so the agent knows what it receives and what to do with it. Combined with cost, endpoint, and input limits, an agent has everything needed to call it correctly.

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 coverage is 100%, so the baseline is 3, but the description adds chain formats (0x, BTC, TRX, SOL and others as OFAC lists them), the 25-per-POST cap, and confirms names are not accepted. That meaningfully supplements the schema's array constraints.

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 (screen a list of wallet addresses against the OFAC SDN list), plus scope (up to 25 per POST) and supported chains. It explicitly names the sibling sanctions_screening and the condition that selects it, so the agent can distinguish the two without opening either 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?

Opens with 'Use when you need to screen a list of wallet addresses' and closes with 'For one address or a name use sanctions_screening' — an explicit when-to-use plus the named alternative and the condition that routes to it. Nothing is left to inference.

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