x402-discovery-mcp

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

Annotations cover safety (readOnly, destructive, idempotent) but description adds critical domain context: 'Free' clarifies no crypto/wallet needed despite x402 payment protocol context, and 'registered' constrains openWorld scope to onboarded services. Adds timing characteristic 'real-time'. No contradictions with annotations.

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?

Two sentences, zero waste. First establishes purpose; second establishes cost constraint. Front-loaded with action verb. No redundant phrases.

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?

Appropriate for a simple health-check tool with output schema present (so return values needn't be described) and rich annotations covering behavioral safety. Purpose, cost, and scope constraints are covered. Only gap is parameter documentation, which is critical given 0% schema coverage.

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 has 0% description coverage (only title 'Service Id'). Description mentions 'any registered x402 service' giving semantic context to what service_id identifies, but fails to name the parameter, describe its format (UUID? URL?), or how to obtain valid values. Insufficient compensation for zero schema documentation.

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?

Specific verb 'Check' plus resource 'health status of any registered x402 service'. Clearly distinguishes from siblings: contrasts with x402_register (creation), x402_discover (finding), x402_attest (verification), and x402_browse (listing). Scope 'registered' limits to existing services.

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?

Second sentence 'Free, no payment required' implies usage constraint (safe to call without funds), relevant for a payment-protocol tool suite. However, lacks explicit when-to-use versus siblings or prerequisites for service_id.

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