Get Fortnox Invoice

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

Annotations already indicate readOnly, idempotent, openWorld, and non-destructive behavior. The description supplements this by specifying the return content (customer info, dates, amounts, line items, payment status), which is useful because there is no output schema. It does not contradict the annotations.

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 well-organized with Args and Returns sections, and the purpose is front-loaded. It is concise but includes some redundancy with the schema (e.g., parameter descriptions), making it slightly less crisp than the ideal, but still efficient.

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?

Given there is no output schema, the description appropriately explains the return value (complete invoice details with specific fields). It also clarifies required vs optional parameters. It does not mention errors or authorization, but for a simple get tool with strong annotations, this is sufficient.

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?

The schema already provides full descriptions for both parameters, and the description largely repeats that information (document_number required, response_format enum). Since schema coverage is 100%, the description adds no significant semantic value beyond what is structured.

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 clearly states a specific action ('Retrieve detailed information about a specific invoice including all line items'), which distinguishes it from list-oriented siblings like fortnox_list_invoices. The verb+resource combination makes it immediately obvious what this tool does.

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 implies usage for a specific invoice (as opposed to listing multiple invoices), but does not explicitly mention when to prefer this over alternatives or any exclusions. No alternative tools are referenced, and the context signals show many sibling tools that could overlap in purpose.

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