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

Annotations already declare readOnly/idempotent/non-destructive, so the description's real contribution is the delivery model: it returns a link, and "the file never passes through the conversation." That is genuinely non-obvious behavior that prevents an agent from expecting PDF bytes back. Gaps remain (link expiry, auth, failure modes), which keeps it below 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?

Three short sentences with the delivery model front-loaded and the API reference last; nothing is padded. The opening sentence is a noun fragment rather than a verb-led statement, which slightly weakens the lead.

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 single-parameter read tool with full annotation coverage and an output schema, describing the link-based delivery and citing the underlying endpoint is close to sufficient. What is missing is differentiation from read_order_pdf and any note on link lifetime, which would matter operationally.

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%, establishing the baseline of 3. The description only implicitly adds meaning via the endpoint template /3/orders/{DocumentNumber}/preview, which usefully implies the parameter is the order's document number — and quietly contradicts the schema's own text "identifies the offer", a mismatch the description never explicitly corrects.

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 order as a PDF" names the resource but never states the action as a verb; the intent (fetch a downloadable link) only emerges from the second sentence. It also fails to distinguish itself from the very similar siblings get_offer_pdf, get_invoice_pdf and especially read_order_pdf, so an agent cannot tell from the description which PDF accessor to pick.

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 when-to-use guidance, no prerequisite stated (e.g. requiring a known DocumentNumber), and no mention of the sibling alternatives such as read_order_pdf or get_fortnox_document. The agent must infer selection purely from the tool name.

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