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

Annotations already declare readOnly, idempotent, non-destructive, closed-world read semantics, so the safety profile is covered. The description adds genuine behavioral context beyond that: results are paginated one page per call, and cross-page aggregation must be requested explicitly via summarize.all_pages.

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 sentences, front-loaded with purpose before the API reference and pagination caveat. Nothing is repeated and every clause carries information an agent needs.

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 not be described, and the schema covers most of the 17 parameters. The one weak spot is the nested summarize object (group_by/sum semantics beyond all_pages), which the description leaves to the schema for a fairly complex tool.

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 82%, so the schema already documents most filter parameters (ean, filter, sortby, sortorder, fields, etc.). The description only adds meaning for one nested parameter (summarize.all_pages); the rest of its parameter semantics rests on the schema, which matches the baseline 3.

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?

"Retrieve a list of articles" states a specific verb and resource, and pins it to a concrete backend (Fortnox GET /3/articles). It contrasts implicitly with the singular sibling get_article via "list", but never names the sibling or the sales-oriented get_sales_by_article, so differentiation is left to inference.

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 description does give real operational guidance: one page per call, and route to summarize.all_pages when totals across all pages are needed. However, it offers no guidance on when to prefer this over get_article or get_sales_by_article, and no note on prerequisites or sensible defaults for a zero-required-param tool.

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