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

Annotations already declare this is a non-readonly, non-destructive mutation, and the description adds important behavior: files are placed straight into the company's Fortnox inbox or archive, the answer reports what arrived, and omitting files produces an upload link instead. It does not cover permission requirements, duplicate handling, or idempotency behavior.

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?

The description is front-loaded with the use case and then explains the two file-passing modes efficiently. It is somewhat long, but the final sentence about chat attachments not becoming voucher documents earns its place.

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 mutation tool with no output schema, the description gives enough context to choose between passing files and requesting an upload link, and it states what the answer will report. It remains incomplete on company-key meaning, folder behavior, and permission/auth details.

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 coverage is 50%, and the description meaningfully clarifies the optional `files` parameter and the two-mode behavior. However, it does not explain `company_key` or `folder`, and only indirectly maps `destination` to inbox/archive, so it does not fully compensate for the schema gaps.

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 states a specific upload action and resource: files/receipts/invoices/documents going into this company's Fortnox inbox or archive. It clearly distinguishes upload behavior from sibling tools that read, list, or download Fortnox documents.

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?

It gives clear usage context with 'Use when the person has a receipt, an invoice, a document or a file that should go into the bookkeeping,' and explains the two upload modes. It does not explicitly name sibling alternatives or exclusion cases, which keeps it below a 5.

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