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

readOnlyHint=true already tells the agent this is a safe read, so the lower bar applies. The description adds only the underlying HTTP route, saying nothing about not-found behavior, auth/scopes, or how the sideloaded includes affect the response.

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 short sentences with the purpose front-loaded and nothing padded. The trailing 'API: GET /orders/{id}.' is largely redundant with the tool name and schema, which is the only minor waste.

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 trivial single-resource fetch with no output schema and a readOnly annotation, the minimal description is close to adequate. It still omits what the returned order contains and how the optional include parameter changes the payload, which an agent calling it would benefit from knowing.

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% — both order_id and include are documented in the schema, including the JSON:API include syntax example. The description adds no parameter meaning beyond that, so the baseline 3 applies.

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?

States a specific verb+resource ('Get a single order') and pins it to an id lookup, which implicitly separates it from lemonsqueezy_list_orders. It does not name the sibling alternatives, but the singular scope is unambiguous.

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?

'by id' implies the precondition that the caller already holds an order id, which is a weak usage signal. There is no explicit when-to-use vs list_orders or guidance on retrieving ids first, so guidance remains implied rather than stated.

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