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

Annotations already declare idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is partly covered. The description adds genuinely non-structured context: no network write occurs, a human must approve, and the response explains how the approved change is dispatched. It does not say where the proposal is stored or how long it persists before approval.

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 purpose, API anchor, and the critical no-side-effect guarantee all front-loaded; no filler. The bare URL is slightly noisy but serves as a pointer to the payload reference.

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?

With annotations covering safety hints and an output schema covering return values, the description supplies exactly what those fields cannot: that this is a proposal-only operation requiring human approval and that the response carries the dispatch instructions. Nothing essential for correct invocation is missing.

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%, so baseline is 3; however the description adds meaning beyond it by showing the expected body envelope ({"SupplierInvoice": {…}}), which the schema only describes as "an object". GivenNumber is still only described in the schema, so no further credit.

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+resource ("Bookkeep given supplier invoice") and pins it to the exact Fortnox endpoint PUT /3/supplierinvoices/{GivenNumber}/bookkeep, which implicitly separates it from the customer-invoice sibling propose_bookkeep_invoice. Differentiation from siblings is achieved via the endpoint and resource name rather than by naming alternatives, so it stops short of a 5.

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?

"Only prepares the change for the person to approve; this tool sends NOTHING to Fortnox" clearly frames when this tool applies (proposal stage, not execution) and points to the follow-up step ("the answer says how the approved change is sent"). It never names the alternative tool (e.g. execute_fortnox_write) or states exclusions explicitly, so it is clear context without full routing.

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