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

Annotations already declare readOnly, idempotent, non-destructive, so safety is covered. The description adds a non-obvious behavioral trait not in any structured field: amounts are bare numbers with no currency attached, and it names the tool needed to resolve currency. That is real value beyond the annotations, though it does not cover e.g. missing-ID error behavior.

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, zero waste, outcome front-loaded followed by the currency caveat. Both sentences earn their place.

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?

No output schema exists, so the description must convey return content, and it does list key fields plus the important currency caveat. It is nearly complete for a single-record getter, with only minor gaps (e.g. error/not-found behavior, pagination is irrelevant here).

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% and the single id parameter is documented as a UUID purchase order ID in the schema. The description adds nothing about the parameter itself, so the baseline of 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 (get) and resource (purchase order) and enumerates the returned fields (amount, status, vendor, linked project), which helps distinguish it from get_purchase_order_line and get_purchase_order_link. It does not, however, explicitly contrast itself with list_purchase_orders or those siblings, so an agent must infer the by-ID single-record scope.

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?

There is no explicit when-to-use/when-not guidance versus the list_ and get_purchase_order_* siblings. It does give one concrete workflow directive — call get_organization_settings for currency_code before stating an amount — which is genuine usage guidance, but usage is otherwise implied by the name.

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