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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is fully covered. The description adds value beyond that by enumerating the returned fields (status, fulfillment status, line count, totals) in the absence of an output schema. It stops short of describing behavior for a nonexistent order number, which would have earned a 5.

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?

One sentence, front-loaded with the action and keyed parameter, ending with the return payload. Every clause carries information and nothing is redundant.

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 one-parameter read-only lookup with complete annotations and no output schema, the description covers what the tool needs: the key, the action, and the shape of the result. The only meaningful omission is what happens when the order number isn't found.

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?

There is a single parameter with 100% schema description coverage, so the schema already explains order_number. The description only reinforces it via "by its order number" without adding format, length, or accepted-variant details beyond the schema; 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 and resource ("look up a sales order") and enumerates what comes back (status, fulfillment status, line count, totals), so the agent knows exactly what the call yields. It doesn't explicitly distinguish itself from the sibling get_orders (list) or get_purchase_order_details, but the single-order-by-number framing makes the scope 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?

Usage is only implied: you call it when you already have an order number and want a point lookup. There is no explicit "use this instead of get_orders when..." guidance and no stated preconditions or failure behavior, which matters given several order-related siblings.

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