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

Beyond the annotations (readOnly/idempotent/non-destructive/openWorld), it discloses case-sensitivity rules per address format, latency ('under 0.1 s, first call up to 1 s'), price (USD 0.002), a shared free-tier pool, and the disclaimer/list_date semantics. This is exactly the extra behavioral context the annotations cannot convey.

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 is front-loaded and the dense detail (formats, return fields, limits, pricing, disclaimer) is largely information-bearing. It is long and reads as a wall of text, but almost every clause earns its place for a paid, caveat-heavy screening tool.

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 enumerates the return fields (matched, matches with sdn_uid/sdn_name/etc., list, list_date, list_addresses, source, disclaimer) and covers scope, caveats, cost, and latency. Nothing an agent needs to invoke it correctly is missing.

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% and there is a single parameter, so the schema already carries the format. The description still adds value by explaining the case-sensitivity distinction between EVM/bech32 (case-insensitive) and base58 BTC/TRX (exact match), which the schema does not state.

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 opens with a specific verb and resource ('screen one crypto address against the US OFAC SDN list's digital currency addresses'), naming the exact list and scope. The word 'one' implicitly distinguishes it from the sibling check_sanctions_batch, so an agent can tell them apart.

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?

It gives rich usage context: scope limits (OFAC SDN crypto addresses only, no other lists, no clustering/ownership/exposure analysis), the caveat that a non-match does not clear an address, and verification guidance. However, it never explicitly names check_sanctions_batch as the alternative for multiple addresses, so routing between siblings 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.