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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely useful context beyond that: a per-call price of $0.002 in Base USDC on eip155:8453 and the required x402 PAYMENT-SIGNATURE header, plus a sub-millisecond latency claim. It stops short of describing what a screening result contains.

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 dense sentences with zero filler, and the core function is front-loaded ahead of the payment mechanics. Every clause carries actionable information for a caller.

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 read-only tool, it covers chains, cost, payment mechanism, and latency, which is most of what a caller needs. The notable remaining gap is that with no output schema and no hint of return shape, an agent cannot anticipate whether it receives a boolean, a risk score, or a match list.

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 both address and addresses are already fully documented in the schema, including chain prefixes and maxItems. The description adds no meaning beyond that, notably nothing about whether the single address and the array are mutually exclusive or how both being optional is handled. Baseline 3 applies.

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: sanctions screening of crypto addresses, naming the exact list (OFAC SDN) and supported chains (EVM, Bitcoin, TRON). That distinguishes it cleanly from screen_domain, screen_prompt, screen_secret, and screen_url, but it never differentiates itself from the sibling screen_batch even though this tool itself accepts an array of up to 25 addresses.

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 explains the payment precondition but gives no when-to-use or when-not-to-use guidance relative to alternatives. An agent cannot tell from this text whether to call screen_address with an array or use screen_batch instead, which is the most likely routing decision it faces.

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