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

With no annotations provided, the description carries full responsibility for behavioral disclosure. It details the two-step paid call pattern, the data sources (URLhaus snapshot + live heuristics), and the nature of the response ('verdict with the rules that fired'). It does not cover potential limitations or rate limits, but the core behaviors are clearly disclosed.

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?

The description is concise and well-structured: it states the core function in the first sentence, describes the return value in the second, and explains the payment flow in the third. No redundant words, every sentence earns its place, and important information is front-loaded.

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?

Given the moderate complexity (multi-step payment, standalone heuristic logic) and lack of output schema, the description sufficiently covers the tool's behavior, return value, and payment workflow. It could further clarify the verdict format or edge cases, but overall it provides enough context for an agent to use the tool correctly.

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?

The input schema already provides 100% coverage with detailed descriptions for all three parameters, including the payment workflow for x_payment. The tool description largely repeats this information, adding no meaningful new semantic value beyond the schema. Baseline 3 is appropriate when schema coverage is high and the description does not compensate with additional context.

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 clearly states it 'Screen a URL against the URLhaus blocklist snapshot plus deterministic live heuristics' with specific method details (redirect chain, host reputation, lookalike patterns). This distinguishes it from sibling tools like address_screen or domain_intel by focusing on phishing/malicious URL screening.

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 provides clear usage context for the payment workflow ('call without x_payment to receive terms...') and explicitly names the free `pricing` tool as an alternative for price discovery. However, it does not explicitly explain when to choose this tool over sibling screen tools, though the title and content make the intended use fairly obvious.

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