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

Goes well beyond the annotations by disclosing side effects: the balance sheet is rolled forward automatically, the income statement restarts at 0, and prior-year result is moved from 2099 to 2091 on the new year's first day only if the year-end closing is already booked, otherwise at prior-year lock. It does not cover permissions/auth requirements or how the 'no gaps' rule surfaces as an error.

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?

Front-loaded with the action and the two modes before the carry-forward mechanics, so the key routing information comes first. The single dense sentence about the 2099/2091 transfer and the trailing 'Scope book. Argument: ...' clause add length, with the argument recap being partly redundant with the schema.

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 2-parameter mutation tool with no output schema, the description covers what it does, when each mode applies, and the accounting side effects. Missing pieces are the return value and any authorization/ownership prerequisites on orgnr, but the essential decision-making information is present.

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 documented in the schema, but year is not. The description compensates by clarifying that year is the end year of the fiscal year (slutår, e.g. 2027), which is genuinely non-obvious for a fiscal-year span. It also restates the required argument pair, though that duplicates 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?

States a specific verb+resource ('Lägg till ett räkenskapsår') and immediately enumerates the only two supported modes: the year after the latest (new year) or the year before the earliest (start bookkeeping in an earlier year without a SIE file). This distinguishes it clearly from siblings like list_fiscal_years, lock_fiscal_year, and transfer_prior_year_result.

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?

Gives explicit conditions for the two modes of use and the hard constraint 'Inga luckor' (no gaps), which tells the agent when the call will fail. It does not name alternative tools (e.g. import_sie for bulk historical years), so the when-not guidance is implied rather than explicit.

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