x402-discovery-mcp

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

Annotations declare read-only, non-destructive, idempotent, and open-world characteristics. The description adds valuable behavioral context beyond annotations: 'Free, no payment required' explains the economic model, and 'Returns full catalog with quality signals' hints at return payload structure despite the existence of an output schema.

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?

Three sentences efficiently front-load the core purpose ('Browse all registered x402 services'), followed by constraints and return value hints. 'Free, no payment required' is slightly redundant but necessary domain context for x402 tools.

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?

Appropriately complete for a single-parameter read operation with a defined output schema. The mention of 'quality signals' adds value without duplicating the output schema contents, and the free/payment status addresses the essential domain-specific context for this protocol.

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?

With 0% schema description coverage, the description minimally compensates by stating the category parameter enables optional filtering. However, it lacks detail on what constitutes valid category values, their format, or semantics, leaving significant documentation burden on the parameter name alone.

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 the tool browses 'registered x402 services' (specific verb+resource) and mentions optional filtering by category. However, it fails to distinguish from the sibling tool 'x402_discover', leaving potential ambiguity between browsing a catalog versus discovering 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?

The phrase 'Free, no payment required' provides crucial usage context for the x402 payment protocol, indicating this is a safe, no-cost operation. While it lacks explicit 'when-not-to-use' guidance or sibling comparisons, the cost transparency serves as clear practical guidance.

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