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

With no annotations, the description carries the burden and discloses the key behavioral facts: this is an information/description tool, the underlying search is a paid x402 capability costing $0.001 USDC on Base, and it returns live listing count, price, and an example call. It does not discuss wallet or payment prerequisites beyond the x402 price, but the core cost and return behavior are clear.

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 tight sentences with no filler: it front-loads the core object being described, then explains the return shape, then clarifies the free-browsing versus paid-API distinction. Every sentence contributes useful context.

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 a zero-parameter, low-complexity info tool with an output schema, the description is complete enough for an agent to know what it describes and what it returns. The output schema covers return details, and the description supplies the important cost and free-versus-paid context.

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 tool has zero parameters, so parameter semantics are not a source of ambiguity. The baseline for zero parameters is 4, and the description adds context around what the described paid search returns rather than needing to explain inputs.

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 names a specific capability, 'AgentPay Directory Search,' and states exactly what it describes: a paid search over verified x402 agent endpoints with live listing count, price, and example call. It distinguishes this from free human directory browsing, though it does not explicitly contrast with the many similarly named directory or marketplace siblings.

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?

It gives useful context that human browsing is free while API search is paid at $0.001 USDC via x402 on Base, which implies when the paid capability matters. However, it does not explicitly say when to call this info tool versus related siblings such as directory_price_check, directory_performance_info, or agentpaystore_directory.

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