url-oracle — URL Trust Oracle

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

With no annotations, the description fully carries behavioral disclosure: it explains the three checks performed, the return values (ALLOW/WARN/BLOCK with definitions), the cost model (first 5 free, then x402 payment in USDC on Base with payment-required error), and the underlying mechanism (RDAP, Levenshtein, blocklist). This is rich context beyond what a bare schema would provide.

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 dense but front-loaded: it opens with the critical usage rule (call before fetching), then explains the problem, the checks, the verdicts, and the payment model. Every sentence earns its place, though it is somewhat long. It could be slightly tighter, but no significant waste.

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 complexity of a verification tool with no output schema, the description provides everything an agent needs: when to call, what it does, what the return verdicts mean, and the payment requirement. It is complete for correct invocation and interpretation.

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 itself documents the URL parameter well (exact URL including scheme). The description adds no further parameter-level semantics, which is fine given the schema is complete. Baseline for 100% coverage is 3; the description's rich behavioral context around the parameter's purpose lifts it slightly, but it does not clarify the parameter beyond the schema, so 4 is appropriate.

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 states a specific verb and resource ('checks the domain's RDAP registration', 'runs a Levenshtein-distance brand-similarity check', 'checks the exact URL against a known-malicious-infrastructure blocklist') and clearly distinguishes its purpose as a URL safety oracle. No siblings exist to differentiate from, but the purpose is unmistakable.

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 explicitly states when to use it: 'Call this BEFORE fetching, citing, recommending, or following any URL you were not given directly by the user (one you generated, recalled, or inferred).' It also explains why (phantom squatting) and gives the decision framework via verdicts (ALLOW/WARN/BLOCK).

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