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 them: results are computed server-side from live Fortnox data and span all pages, so the agent knows pagination is already handled and the data is current.

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, front-loaded segments: definition, example question, provenance note. No filler sentences. The mixture of Swedish body text and English parameter docs is slightly awkward but does not cost space.

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 prose. With annotations covering safety and the schema covering all four parameters and their defaults, the description adds exactly the missing pieces: sort order, data freshness, and full-page coverage.

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%, so the baseline is 3. The description's "konto för konto" hints that from_account/to_account bound the range, but it adds no detail on the top-N cap or how the date parameter selects the comparison year beyond what the schema already says.

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 operation: an account-by-account comparison against the prior year, ordered by largest change first. The verb+resource+scope are clear. It does not explicitly distinguish itself from the sibling get_deviations_vs_last_month, which is the one obvious confusion risk.

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 ("Vilka kostnader har ökat mest mot förra året, och varför?") implicitly signals the use case without naming when not to use it. There is no reference to the near-identical get_deviations_vs_last_month sibling, so the agent must infer the choice from the tool name alone.

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