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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely useful context beyond that: the result is computed server-side from live Fortnox data and aggregates over all pages, telling the agent there is no pagination or staleness concern. It does not describe failure modes or data-freshness latency.

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, front-loaded with the definition, followed by the example and the data provenance. The example question largely restates the definition, which is mild redundancy but serves as a routing trigger, so the sentence still earns its place.

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 present, return values need not be explained, and annotations fully cover safety semantics. The description supplies source-of-truth and scope ('all pages'), leaving only minor gaps around what counts as 'obokfört' or 'förfallet' and how they are grouped in the response.

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% and the single optional date parameter is fully documented in the schema, including the default of today and the retroactive behavior for past dates. The description adds nothing about the parameter, so the baseline of 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?

The description states a concrete composite output — unbooked items, unpaid items, and overdue items in a single answer — which is more specific than a generic 'report' label and implicitly differentiates it from single-concern siblings like get_payables_aging or get_receivables_aging. It stops short of naming those siblings explicitly, so an agent must infer the distinction.

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 embedded example question ('Gör en månadsgenomgång: vad är obokfört, obetalt och förfallet?') gives a concrete trigger, so usage is implied rather than stated. There is no when-not guidance and no named alternative for agents who only need one of the three components.

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