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

Annotations already declare destructiveHint=true, readOnlyHint=false and idempotentHint=true, so the safety profile is covered. The description adds real value beyond them by disclosing the precondition (invoice must be unpaid) and the actual effect (the bokföringsverifikat is reversed), which the annotations do not convey.

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?

Very tight and front-loaded: the action and its effect come first, scope second. The trailing 'Argument: orgnr, invoice_id' is redundant with the schema's required fields and is the only wasted fragment.

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 destructive, idempotent mutation with no output schema and annotations covering safety, the description supplies the two things an agent actually needs: the precondition and the accounting consequence. Nothing critical 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 50%: orgnr is fully documented in the schema including a hint to use list_companies, while invoice_id has no schema description at all. The description only restates 'Argument: orgnr, invoice_id' without adding format, lookup, or type meaning, so it does not compensate for the undocumented parameter.

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 resource ('Makulera en kundfaktura') and adds the behavioral distinguishing detail that it applies to unpaid invoices and reverses the accounting voucher, which separates it in spirit from credit_customer_invoice. It never names a sibling explicitly, so it stops short of the top band.

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 parenthetical 'obetald' gives an implied precondition and 'Scope book' hints at the operating scope, so an agent can infer when this applies. However, there is no explicit when-to-use versus credit_customer_invoice or cancel_supplier_invoice, and no stated exclusions for paid invoices.

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