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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description still adds real behavioral value: results are computed server-side from live Fortnox data and cover all pages, telling the agent pagination is handled internally. It adds nothing about latency or data freshness limits, which keeps it at 4.

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 list is front-loaded, and the example question plus data-source note follow in a tight block with no filler. The one inefficiency is the example question, which occupies a full sentence for a single trigger phrase. The Swedish/English mix with an otherwise English toolset slightly slows parsing but does not waste words.

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?

An output schema exists, so return values need no explanation; annotations cover the safety profile; there are no parameters to document. The description fills the remaining gap by saying what is reconciled, against what source, and that it is computed live over all pages. Nothing an agent needs in order to call it correctly 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?

The tool takes zero parameters, which is the baseline-4 case. There is nothing for the description to disambiguate, and the empty schema is consistent with the description's claim that everything is computed server-side.

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 names a concrete operation (balance reconciliation) and enumerates the specific account groups covered: AR/AP against the subledger, bank against inbox statements, and tax/payroll/VAT accounts. That is far more than a restatement of the name. It stops short of 5 because it never contrasts itself with close siblings such as reconcile_supplier_statement, reconcile_card_transactions or get_receivables_aging, so an agent must infer the boundary from the field list alone.

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 ('Stämmer balanskontona? Gör en balansavstämning.') gives a concrete trigger scenario, which is clearer than mere implied usage. It gives no exclusions or named alternatives, so it lands at 4 rather than 5.

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