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

With no annotations, the description carries full burden and delivers: it states the tool 'probes observable reality' across five dimensions, returns a 0-100 rating and A-F grade, signs responses with Ed25519, publishes weights/method, and discloses the conflict-free fee model. This gives the agent strong expectations of side effects, output format, and pricing, going well beyond a generic 'rate a service'.

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 sentences, each earning its place: purpose, method, transparency/conflict-of-interest rationale, and usage guidance. The 'Moody's' analogy front-loads the concept, and the pricing is tucked at the end. No fluff or repetition.

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?

The tool has one parameter and no output schema, but the description covers input (URL), output (rating, grade, signature), behavioral details (probes live/discoverable/payable/breadth/transparency), and pricing. It communicates all essential information an agent needs to decide whether to invoke and what to expect, even without an explicit return-structure schema.

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 already documents 'target' with 100% coverage, so baseline is 3. The description adds value by explaining what 'target' means in context ('Point it at a URL'), the URL type (service/agent or x402 base), and what the tool does with it ('probes observable reality'), enriching the bare schema description.

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 'Signed, conflict-free rating of any agent/x402 service' — a specific verb ('rating') and concrete resource (any agent/x402 service). It further distinguishes itself from sibling tools like onyx_agent_verify or onyx_contract_audit by framing itself as 'Moody's for the agentic web' and contrasting its transparent method with 'everyone else's hidden N=1 score'.

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?

Explicitly states 'Use it to vet a service or counterparty before you route, integrate, or pay.' This provides clear when-to-use guidance. It does not explicitly list alternatives or negative use cases, but the description's context (vetting before integration) and the tool's distinctive rating focus sufficiently imply when it is appropriate.

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