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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior: the exact sections produced and an ephemeral .txt download link valid for one hour, plus that it is free on every tier. It does not explain why the tool is non-read-only (the link artifact) or what happens on a bad PO id.

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, front-loaded with the transformation and its contents, with the link and pricing details after. Nearly every clause carries information, though 'Free on every tier' is commercial framing rather than invocation guidance.

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, and the description compensates well by enumerating the rendered sections and the download-link delivery mechanism. Combined with a fully documented input schema, an agent has enough to call it correctly; only error behavior is left unstated.

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 all three parameters are described there, including the PO-2026-0001 id format and the greeting/sign_off defaults. The description adds nothing about greeting or sign_off customization, so 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 transformation (turn a purchase order into a plain-text order) and enumerates exactly what the output contains: line table, VAT lines, total, delivery line. The email-paste framing implicitly separates it from the PDF sibling, but it never names purchase_order_pdf or purchase_order_get as alternatives.

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 'to paste into an email' framing gives a clear intended use case, so an agent can infer when this is the right renderer. However, there is no explicit when-not guidance and no named alternative for PDF-style output, which matters given the sibling cluster of purchase_order_get/pdf/list.

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