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

Annotations already cover readOnly, idempotent, closed-world, and non-destructive, so the bar is lower. The description adds genuinely useful behavior beyond them: the result is computed server-side from live Fortnox data and aggregates over all pages, so the caller knows no pagination loop is needed.

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?

Content is front-loaded: what it returns, then when to use it, then parameter meaning, then provenance. It is a single dense paragraph that partially repeats the schema's defaults, which keeps it from being maximally tight.

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 no explanation, and the description covers scope, triggers, parameter meaning, and data provenance. Minor gaps remain (e.g. whether results span all companies or the connected company, and what 'inbox' comprises), but nothing blocks a correct call.

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% and the schema already declares the defaults (7 days, yesterday), so the description's restatement of default values is largely redundant. It does help by glossing the Swedish parameter names in English, but adds no formats or edge cases beyond the schema.

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?

It names a specific resource and enumerates exactly what is returned: new and changed supplier invoices, customer invoices, incoming/outgoing payments, upcoming due items, and inbox contents. An agent can distinguish it from narrower siblings such as get_inbox_folder or get_cash_forecast without opening a schema.

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?

It gives explicit triggers ('how things look today', 'what has happened since a given day') plus a concrete example question in Swedish. It does not name what to use instead for narrower questions (e.g. payables aging or cash forecast), so it falls short of full when/when-not routing.

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