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

Goes well beyond the annotations: it discloses that the customer is emailed (external reach), that each call is confirmed by default with an option to disable, that text is prefilled unless message is passed, that the deadline derives from the Mahnfrist setting, and that a Cotlet API key with app access is required. This is exactly the non-obvious behavioral context annotations cannot carry.

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 opening idea is stated twice in near-identical sentences ('Create the next reminder for an overdue invoice and email it...' then 'Creates the next reminder for an invoice and sends it by email'), which is wasted space. Core content is front-loaded and otherwise dense, but the redundancy costs it.

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?

No output schema exists, yet the description focuses on behavior rather than return values, so an agent lacks information about the response. Everything else an agent needs to call it correctly, including confirmation and auth requirements, is present.

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 100%, so both parameters are already documented. The description reinforces the message default ('prefilled by sevdesk unless you pass message'), which largely duplicates the schema's 'Default: the sevdesk standard text,' and adds no syntax or format detail beyond it, so baseline 3 applies.

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 verb and resource (create the next reminder for an overdue invoice) and adds the escalation semantics (first is a Zahlungserinnerung, later ones are Mahnungen). It also discloses the side effect (emails the customer), so an agent knows exactly what the tool does without opening the schema.

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 clearly frames the trigger condition ('overdue invoice') and the escalation rule (first vs. later reminders, requires an invoice that already got a reminder), plus the Buchhaltung plan requirement. It stops short of naming alternative siblings like sevdesk_send_invoice or sevdesk_mark_invoice_paid to route the agent, leaving that to inference.

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