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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so 'Read-only' in the text is redundant. The description does add useful context beyond annotations: the endpoint (GET /3/inbox) and the kinds of items returned. It says nothing about pagination behavior despite page/limit/offset parameters.

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 the operation and its scope, followed by the usage trigger and an API reference. The only waste is repeating 'Read-only' already covered by annotations.

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 and annotations cover the safety profile, so return values and risk need no explanation. However, for a list tool with page/limit/offset/sort parameters, the absence of any paging or result-size guidance leaves a real gap for an agent that may need to enumerate a large inbox.

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?

Five optional parameters exist with only 40% schema description coverage (sortby and sortorder are described; page, limit, offset are not). The description does not mention pagination or sorting at all, so it fails to compensate for the coverage gap.

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 gives a specific verb and resource ('Lists the root of the Fortnox inbox') and enumerates the contents (folders such as supplier invoices, receipts, expenses, vouchers; plus files). The word 'root' implicitly distinguishes it from get_inbox_folder, but no sibling is named explicitly, 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?

'Use when the person asks what is in the inbox' is a clear, concrete trigger condition. It offers no exclusions or guidance about when to prefer list_unprocessed_inbox or get_inbox_folder instead, which keeps it short of a 5.

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