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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals that the tool costs 1¢ USDC on Base and that in DEMO_MODE the payment is simulated, which are important behavioral traits. It does not explain failure behavior or return format, but for a simple demo this is sufficient.

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?

The description is three concise sentences, each earning its place: the tool's identity, the cost, and the usage context plus demo mode note. No filler or redundancy.

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?

Given the tool's simplicity (one optional parameter, no output schema, no annotations), the description covers purpose, cost, payment rails verification, and demo mode. It does not state what the response contains, but for a greeting demo this is likely self-evident.

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 input schema already provides 100% coverage for the single optional 'name' parameter with a clear description. The tool description does not add any additional parameter semantics beyond the schema, so the baseline of 3 is appropriate.

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 'The canonical x402 hello-world demo' clearly states it is a greeting/payment demo, and the title 'Say hi to Wild Wallet' conveys the action. It distinguishes itself from siblings like listItems and requestMerge by being a payment test, not a data or merge operation.

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 description explicitly says 'Useful for verifying your MCP client can pay Wild Wallet's public rails before you commit to a merge,' providing clear contextual guidance on when to invoke the tool. It does not mention alternatives or exclusions, but the use case is well-scoped.

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