x402-discovery-mcp

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

Adds valuable context beyond annotations: 'Free' (cost), 'discovery index/catalog' (external destination matching openWorldHint), and 'discoverable by agents' (visibility outcome). Could improve by noting idempotency=false behavior (re-registration creates duplicates?).

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 efficient sentences. Front-loaded action, zero redundancy. 'Free.' as standalone is punchy and effective.

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?

Adequate for a registration tool with output schema available, but gaps remain given 7 undocumented parameters. Should mention authentication needs implied by wallet_address or registrar obligations.

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 fails to compensate. Mentions 'Free' (vaguely related to price_per_call) but doesn't explain capability_tags format, network enum values, or wallet requirements despite 7 parameters needing 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?

Excellent specificity: 'Register' (verb) + 'x402 service' (resource) + 'discovery index' (scope). Distinguishes clearly from siblings browse/discover (search) and attest (verify).

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?

Implies usage through outcome description ('Your service will appear in the catalog'), mentions 'Free' as cost signal, but lacks explicit when-to-use vs siblings or prerequisites like wallet setup.

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