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

Beyond the read-only and open-world annotations, it discloses that health data comes from unpaid probes run every 10 minutes and defines live as receiving HTTP 402 with parseable terms. This provides valuable freshness and reliability context for interpreting the results.

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 compact sentences front-load the action and resource, then provide the probe method, cadence, liveness definition, metrics, and intended use. The first sentence is dense but contains no filler.

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 read-only tool with no required parameters and an output schema, the description supplies the operational context needed to invoke and interpret it correctly. The data source, cadence, liveness criterion, key metrics, and pre-payment selection workflow are all covered.

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?

The schema already documents all three parameters, including defaults, bounds, and CAIP-2 network syntax. The description adds the precise meaning of live and the probe cadence, which helps interpret liveOnly, though it adds no further guidance for limit or network.

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 uses a specific verb and resource—listing x402 paid API endpoints—and explains the health ranking and reported metrics. Its domain and purpose are clear, but it does not explicitly differentiate itself from the sibling mcp_readiness_check.

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 second sentence gives a concrete use case: choosing a working paid endpoint before paying. It does not explain when not to use the leaderboard or when mcp_readiness_check would be the better alternative.

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