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

Annotations already declare the safety profile (readOnly=true, idempotent=true, openWorld=true, destructive=false), and the description adds genuinely new behavioral context the annotations lack: a free-sample quota and per-call cost of $0.01 USDC via x402, which is a rate/billing constraint an agent should know before invoking. It doesn't describe scoring behavior or what a match result contains, but the pricing detail is meaningful added value.

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 short sentences with no filler, and the core scope ('US OFAC SDN list only') is front-loaded ahead of the secondary pricing note. Every clause earns its place.

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?

An output schema exists, so return values need not be explained, and the description covers scope and cost for a simple two-parameter tool. The main gap is the absence of any guidance on aggregating this with the UK or general screening siblings, but for a low-complexity tool the definition is largely complete.

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 schema already documents both 'name' and 'threshold' (with its default of 80). The description adds no additional parameter meaning beyond what the schema provides, so the baseline of 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?

The description specifies the exact data source: 'Potential matches on the US OFAC SDN list only.' Combined with the title and name, an agent can tell this screens names against the US OFAC list, and the word 'only' distinguishes it from the UK-list sibling sanctions__screen-uk. It stops short of stating the verb/resource explicitly (the title carries that), so 4 rather than 5.

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 phrase 'US OFAC SDN list only' implicitly routes the agent away from sanctions__screen-uk, but the description never explicitly says when to choose this tool over sanctions__screen or the other sanctions siblings. No prerequisites or exclusions are spelled out; the routing is inferred rather than stated.

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