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

Annotations already declare readOnlyHint: true, so the safety profile is covered. The description adds the REST endpoint and mentions support for expand and fields, but 'Supports expand and fields' merely repeats what the schema already documents. It does not disclose additional behaviors like error handling, response format, or rate limits, so the added value is modest.

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 highly concise: two sentences (three if counting the endpoint) that immediately state the purpose, then mention parameter customization and the underlying API endpoint. No filler or redundancy. Each sentence adds distinct value, and the key information is front-loaded.

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 get-by-id tool with robust schema annotations and a readOnlyHint, the description adequately covers purpose, input flexibility, and underlying API context. It does not explicitly state the return type or error behavior, but the tool name ('Get an order') and the action ('Fetch a single order') imply the response is the order object. Given the absence of an output schema, a brief note on the return value could be helpful, but it is not a major gap.

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 each parameter is already documented. The description clarifies that 'id' can be an order number or record id (repeating schema) and that expand/fields are supported (also in schema). It adds no new semantic details beyond what the schema provides, keeping the score at the baseline of 3.

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 verb and resource: 'Fetch a single order by its record id or its order number.' This distinguishes it from sibling tools like swell_list_orders (multi-order) and swell_update_order (mutation). It also names the REST endpoint (GET /orders/{id}) which adds specificity.

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 phrase 'Fetch a single order' establishes a clear context for when to use this tool (when you need one specific order). It doesn't explicitly mention exclusions or alternatives, but the described scope is self-evident. The endpoint and single-order wording imply it is not for listing or updating. Sibling names further clarify the distinction.

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