list_x402_endpoints

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

With no annotations, the description carries the full burden and does well: it discloses which sources are fetched live from OpenAPI specs, that the directory contains unverified third-party entries that are hidden by default, and that cost data from live specs is only a tier rather than an exact price. It omits return shape, pagination, and any rate-limit/caching behavior.

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?

Front-loads the core purpose in one sentence, then uses a scannable bulleted source list rather than prose. It is somewhat long for a list tool, and the source bullets duplicate the enum values, but each line adds information an agent would otherwise have to discover by calling.

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?

For a six-parameter, zero-required discovery tool with no output schema, the description covers sources, live-vs-static behavior, verification defaults, and the pricing caveat. The remaining gap is that it never hints at what an endpoint record contains (path, price, category, verification status), which matters given there is no output 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 coverage is 100%, so baseline is 3, but the description adds real meaning beyond the schema: it explains what each `source` enum value actually contains (DeFi analytics, AI inference, registry, messaging) and clarifies the security implication of `includeUnverified`. It does not touch `search`, `category`, `showFreeOnly`/`showPaidOnly`, though the schema documents those adequately.

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?

States a specific verb and resource ("List x402 API endpoints") and immediately enumerates the five distinct sources it aggregates, so an agent knows exactly what corpus this returns versus a single-endpoint tool. The distinction from probe_x402_endpoint and execute_x402_endpoint is reinforced by pointing at probe for pricing.

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?

Gives clear operating guidance: "use probe_x402_endpoint for the exact price" and "probe before paying" for unverified directory entries, plus a cross-sell tip to earning_opportunities. It does not explicitly state when to reach for execute_x402_endpoint instead, so routing guidance is strong but not exhaustive.

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