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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds useful non-obvious context: this returns an 'API pass key', i.e. sensitive credential material, and that data exists only for fulfilled orders – a meaningful behavioral disclosure beyond the 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?

Two short sentences: the operation and its return payload are front-loaded, followed by a compact example. No filler, nothing to trim.

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?

With only one optional string parameter and an output schema present, the description covers what an agent needs to invoke it correctly. The main residual gap is error behavior for non-fulfilled or missing orders, plus the mismatch between 'by order_id' and the schema marking it optional.

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 coverage is 100% and order_id is documented as 'Completed order identifier', so the baseline would be 3. The description adds a concrete format example ('ord_1'), which is genuine value beyond the schema, though it doesn't reconcile the fact that order_id is not marked required.

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 ('Retrieve') and resource ('fulfilled order receipt and API pass key'), and the 'order' resource is clearly distinct from the cart/checkout/catalog siblings. It doesn't explicitly contrast itself with any named sibling, but an agent can identify the operation without opening the schema.

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 word 'fulfilled' implies this only applies to completed orders, which is a soft usage constraint, and the example shows the calling shape. However, there is no explicit statement of when to use this versus get_cart/get_checkout or what to do for unfulfilled orders.

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