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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description adds the sort order (newest first) plus a detailed inventory of returned fields including sums in öre. With no output schema, this return-value disclosure is genuinely useful context beyond the annotations, though 'Läser bara, ändrar inget' only restates readOnlyHint.

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-loads purpose, then usage/alternatives, then return contents, then the read-only note. Each sentence carries distinct information, though the return-field enumeration is dense and slightly overlong.

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 two-parameter list tool with no output schema, the description covers filtering, ordering, sibling differentiation, and the shape of the returned data (fields, totals, currency unit in öre). Nothing an agent needs to invoke 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?

Schema description coverage is 100%, so both orgnr and status are already fully documented, including status values and the orgnr format. The description mentions optional status filtering but adds no syntax or meaning beyond the schema, so the baseline 3 applies.

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 (Listar) and resource (kundfakturor), plus scope details (nyast först, valfritt filtrerade på status). It explicitly distinguishes itself from get_customer_invoice (single invoice) and customer_outstanding (unpaid per customer), so an agent can pick the right tool without opening schemas.

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?

Names concrete use cases (hitta en faktura, se vad som är obetalt) and routes to the correct alternatives by condition: get_customer_invoice for a single invoice and customer_outstanding for per-customer unpaid. The alternative selection logic is explicit rather than implied.

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