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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by disclosing that results are computed server-side from live Fortnox data and aggregate over all pages, so the agent knows it is authoritative and already paginated. It omits any note about latency, rate limits, or result size.

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?

The scope statement is front-loaded, followed by the source/pagination note and one concrete example question. The long em-dash enumeration is dense but every clause carries information; nothing is padded.

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 an output schema covering return values and full annotation coverage, the description supplies what is missing: what the tool computes (live data, all pages), what scopes exist, and a realistic trigger question. An agent has enough to call it correctly without guessing.

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 description coverage is 100%, so the baseline is 3 and the schema already documents kund, status, todate and fromdate precisely. The description mostly restates the status enum and the returned fields rather than adding format or edge-case meaning (e.g. how partial name matching behaves, or how dates interact with status).

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 (fetch customer invoices) and enumerates the scoping options: a customer or a status among obetalda/förfallna/ej_skickade/betalda/alla, with amount and due date returned. It does not, however, distinguish itself from close siblings such as list_invoices, check_invoices_exist, or find_supplier_invoices, so an agent must infer the boundary itself.

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?

Usage is only implied through the example question ("Har Nordic betalat sina fakturor? Vilka kundfakturor är inte skickade?"), which usefully illustrates the receivables-collection scenario. There is no explicit statement of when to prefer this over list_invoices or get_receivables_aging, and no exclusions or prerequisites are given.

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