Send Fortnox Invoice by Email

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

The description adds meaningful behavioral context beyond the annotations: it specifies that the email goes to the customer's configured address and that a confirmation is returned. The annotations already indicate openWorldHint (external side effect) and destructiveHint false, and the description aligns with these, providing clarity on the specific side effect without contradicting 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 compact, front-loaded with the primary purpose, and includes a clear Args section and Returns statement. It avoids unnecessary verbosity, though it could be slightly tighter by omitting the redundant parameter repetitions, but overall it 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 simple two-parameter tool with no output schema, the description sufficiently explains the tool's effect (sends email to configured address) and return value (confirmation). The annotation openWorldHint already signals external interaction, and the description complements it with specifics. It does not mention edge cases like missing email configuration, but the level of detail is appropriate for the tool's simplicity.

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?

Both parameters are fully described in the input schema, and the description merely repeats their names and types ('document_number', 'response_format') with minimal additional context. Since schema description coverage is 100%, the baseline of 3 applies; the description does not add significant semantic value beyond the schema.

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 begins with 'Send an invoice to the customer via email', which clearly identifies the action (send), resource (invoice), and delivery method (email). This distinguishes it from sibling tools like fortnox_get_invoice or fortnox_create_invoice, as no other sibling is focused on emailing invoices.

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 clearly states that this tool sends an invoice to the customer's configured email address, providing clear context for when it should be used. It does not explicitly mention alternatives or exclusions, but the purpose is straightforward and unambiguous within the sibling set, so it meets the 'clear context, no exclusions' bar.

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