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 burden is covered. The description adds real context beyond that: results are computed server-side from live Fortnox data and span all pages, telling the agent there is no pagination to manage and the figures are 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 compact sentences: scope first, an example question second, provenance last. Each sentence earns its place, and the resource name is front-loaded; only the somewhat telegraphic middle clause costs it a point.

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 full schema coverage, an output schema present, and rich annotations, everything an agent needs is covered; the description supplies the one thing structured fields cannot — what business question the tool answers and that data is live across all pages.

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 schema already documents period, fromdate, todate and stort_belopp (including the 10,000 kr default). The description adds nothing further about these parameters, which is acceptable given the schema quality but is the baseline rather than added value.

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 the resource (periodiseringar/accruals) and spells out the three things checked: planned accruals, whether they are booked, and large invoices on advance-payment accounts that lack one. This is a specific check rather than a restatement of the name, though the compressed Swedish phrasing makes it slightly harder to parse at a glance.

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 ("Har vi periodiserat det som ska periodiseras? Bokförs periodiseringarna?") implies the user intent this tool answers, which is genuine usage signal. However, no alternatives or exclusions are named, so an agent must infer when this beats check_vat, get_month_end_review, or get_year_end_package.

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