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

Annotations already declare readOnlyHint=true, idempotentHint=true and closed-world, so safety is covered. The description adds one genuinely useful behavioral note: each row carries 'what is still to arrive,' i.e. pending receipt quantities. It does not say whether rows are grouped or flat, or how large the result can be.

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?

A single short sentence with no filler, and the scoping idea is front-loaded. It is terse rather than padded — the problem is under-specification, not verbosity.

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, no-output-schema list tool this is nearly sufficient, but with no output schema the agent must guess the return shape; 'what is still to arrive on each' is the only hint and is vague about whether it is a quantity, a date, or nested lines.

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 the single enum parameter is fully documented, so the baseline is 3. The description's 'by state' is consistent with the parameter but adds no syntax, default-behavior, or omission semantics beyond the schema.

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 fragment 'Orders by state, with what is still to arrive on each' conveys scope (grouping orders by state plus outstanding receipts) but has no verb and never says 'purchase orders' — the title carries that. Against siblings like p2p_goods_received, p2p_bill_match and p2p_unbilled_receipts, the agent has to infer that this is the read/list endpoint for POs.

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 statement of when to use this versus p2p_goods_received, p2p_bill_match, or p2p_unbilled_receipts, nor any mention that omitting the state parameter returns all states. The agent gets no routing hints at all.

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