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

Annotations already cover the read-only, idempotent, non-destructive profile, so the description must add something else — and it does: the recommended polling cadence, the terminating condition (`terminal` field), and what each terminal outcome carries (confirmation + signed receipt for delivered, refund txid + signed receipt for refunded, plus refund_failed). That is meaningful context beyond the annotations. It does not say whether polling too fast is throttled or how long orders typically take.

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 sentences, no filler, and the actionable polling rule plus the terminal-state enumeration are front-loaded with no redundant restatement of the tool name or schema.

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?

There is no output schema, so the description must carry the return-value burden, and it does explain the terminal states and what accompanies each. It leaves the non-terminal response shape (what fields exist while pending, beyond the implied `terminal` flag) unstated, which is the main remaining gap for a polling tool.

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?

One parameter with 100% schema description coverage; the schema already explains that orderId is the value returned by buy. The description adds nothing about the parameter, 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?

"Check an order" names the resource but with a generic verb; the second sentence rescues it by defining exactly what this tool resolves to (terminal states: delivered, refunded, refund_failed). An agent can tell this is the post-purchase status-polling tool distinct from buy/quote, though the description never explicitly names those siblings.

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?

Gives concrete operational guidance: poll every ~3 s and stop when `terminal` is true. That is real when/how-to-use instruction for the polling loop. It stops short of explicit exclusions or naming alternatives (e.g., "use verify_receipt to validate the receipt independently"), so it does not reach a 5.

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