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

Annotations already cover read-only, idempotent and closed-world behavior, so the bar is lower; the description still adds meaningful context beyond them with the exact-match-only limitation (no fuzzy or probabilistic matching) and the free/cost signal. It stops short of describing what a hit versus a miss returns, but the limitation disclosure is genuinely useful.

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?

Four short clauses, front-loaded with the cost and the core question, followed by the scope limit and the routing alternative. Nothing is redundant or padded.

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 single-parameter, read-only screening tool whose annotations carry the safety profile, the definition covers purpose, scope, and routing completely. The only gap is that with no output schema present, the description does not indicate the shape of the answer (boolean verdict vs. match details), which an agent calling it would benefit from.

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 the schema already documents the single address parameter including accepted prefixes (bc1..., 1..., 3...). The description adds no syntax, format, or batching detail beyond that, so the 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 check ('Is this Bitcoin address on the OFAC SDN sanctions list or a known ransomware payment address?') with an explicit scope limit ('Exact list matches only'). It also names the sibling it is not, so an agent can select between it and bitcoin_address_risk without reading 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?

Gives explicit when-to-use ('Exact list matches only') and an explicit alternative with the condition that selects it ('For ownership clusters, sweeper bots and laundering patterns use bitcoin_address_risk'). The 'Free' marker adds a cost-based selection signal.

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