Income statement (resultaträkning)

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

Annotations already declare readOnly/idempotent/destructive=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it is built from the SIE export, matches the books exactly including manual vouchers, and revenue is positive while costs are negative — a sign convention the annotations cannot convey.

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?

Dense and front-loaded — the purpose comes first, then the grouping, sign convention, and data provenance. Slightly run-on but every clause carries information; nothing is padding.

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 no output schema, the description usefully sketches the return shape (grouped by account class, per-account lines) and the sign convention. The only real gap is period-boundary semantics for the two date parameters, which is minor for a read-only report.

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 0%, and the schema only conveys the date format via a regex pattern. The description adds that the range is arbitrary ('any date range') but does not state whether to_date is inclusive, which matters for a period report. Partial compensation only.

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 resource and output shape: 'Profit and loss for any date range, grouped by BAS account class with per-account lines', and even enumerates the line categories. An agent can tell this apart from balance_sheet, though no sibling is named explicitly.

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 implied by 'for any date range' and the revenue/cost framing, but there is no explicit when-to-use statement, no exclusion, and no pointer to alternatives such as account_totals_by_month or balance_sheet for other reporting needs.

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