agent_service_directory

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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses the $0.05 cost and the WALLET_PRIVATE_KEY requirement, which are critical for an agent to decide whether to call. It also specifies the output fields and machine-readable nature, though it omits error cases or pagination 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?

The description is two sentences, front-loads the cost warning, and packs essential details such as content, use case, filter, and auth requirement without any redundant words. It is concise and well-structured.

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 simple one-optional-parameter directory lookup, the description covers purpose, when to use, cost, auth requirements, and expected output content. It lacks explicit error handling details but is otherwise complete enough for an agent to decide and invoke correctly.

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 covers the category parameter with its allowed values (100% coverage), but the description adds behavioral meaning by labeling it an 'Optional category filter' and repeating the categories in a practical context. This goes slightly beyond the schema's bare value list.

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 clearly states the tool provides a machine-readable registry of production x402 services, listing name, category, route count, and price range. This distinguishes it from sibling tools like list_capabilities and get_endpoint_spec, which focus on capability listing or endpoint details.

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 states it is useful for an agent deciding which paid tool/service to reach for next, giving a clear when-to-use context. It does not mention alternative tools or exclusions, but the use case is well-defined and sufficient.

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