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

Annotations only cover readOnly/idempotent/openWorld; the description adds the material behavioral facts an agent cannot get elsewhere: it costs $0.02 USDC on Base via x402, and it returns x402 payment requirements unless payment_signature is supplied. That payment-gating flow is exactly the kind of non-obvious behavior this field should capture.

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-loads purpose, then usage, then price/payment mechanics in four compact sentences with no filler. The '[Compliance & counterparty]' tag and sample path are slightly incidental but cheap, so it stays tight.

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 person-screening tool with no output schema and full schema coverage, the description covers purpose, trigger, and payment flow. It only describes the payment-requirements return path, not the shape of the actual PEP match results (candidate list, match scoring), which is a modest remaining gap.

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 all five parameters are already documented in the schema and the baseline is 3. The description only references payment_signature tangentially ('unless payment_signature is given') and adds no syntax or format meaning beyond the schema for name, limit, country, or birth_year.

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 ('Check whether a person is a politically exposed person (PEP)') and scopes it to KYC/AML onboarding, so the agent can tell it apart from the sanctions siblings by entity type. It never names screen_sanctions or batch_sanctions_screen explicitly, so the differentiation is conceptual rather than explicit.

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 clear trigger context: 'Use when onboarding a customer, director or beneficial owner.' That is a real when-to-use signal, but there are no exclusions (e.g. 'for sanctions lists use screen_sanctions instead') and no prerequisite guidance beyond the payment note.

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