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

With annotations already declaring readOnlyHint=true and destructiveHint=false, the description goes further by explaining the accountless nature ('No account or API key exists or is needed'), the payment model (x402, priced per call), and reiterating that this tool 'only discovers'. This adds substantial context beyond the structured annotations, such as the operational requirement for a wallet when actually paying. There is no contradiction with annotations.

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 a single, well-structured paragraph of three sentences. It front-loads the core purpose, then provides essential context about accountlessness and payment, and ends with the return structure. Every sentence contributes information without redundancy or filler. It is concise yet comprehensive.

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 listing tool with no output schema, the description covers the essential details: what it lists, the accountless and payment model, and the return shape (including pagination fields like has_more, next_offset). It does not explicitly explain how to paginate iteratively, but the return object implies it. Given the tool's simplicity and the richness of the description, it is nearly complete; a small gap is the lack of any mention of rate limits or error handling, but those are not expected for discovery tools.

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 description coverage is 100%, so the baseline is 3. The tool description does not add parameter-specific details beyond what the schema provides, but it does offer contextual hints through the example return object (e.g., offset, has_more) that relate to pagination parameters. It does not improve on the schema descriptions, so a 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 clearly states the tool's function: 'List services on the code402 gateway storefront', with a specific verb ('List') and resource ('services'). It distinguishes itself from siblings by mentioning 'first-party APIs and third-party seller listings' and explicitly says 'this tool only discovers', which sets it apart from payment or creation tools. The GET /v1/services path adds further clarity.

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 provides clear usage context by stating this tool is for discovery only ('this tool only discovers') and clarifies that paying for services requires an x402-capable client with the buyer's own wallet. It also notes that no account or API key is needed, which guides the agent on authentication. However, it does not explicitly name alternative tools or specify when not to use it, but the sibling list and the 'only discovers' phrasing give sufficient implicit guidance.

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