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

Adds substantial context beyond the annotations: the consequence of skipping it ('ohne ihn laeuft das Konto ab'), the fact that credentials arrive out-of-band by email, and that a human supplies the code so no mailbox access is required. It stops short of covering idempotency or what happens on a stale/invalid code, which the annotations flag as non-idempotent.

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?

Triggers and the core constraint are front-loaded, and each sentence carries useful routing or setup information. Minor waste in the trailing '| EN: renew, account' keyword tag and the German/English mix, but density is high.

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 single-parameter lifecycle mutation with annotations and no output schema, the description covers when to call, how to obtain the token, and the failure consequence. It does not indicate what the call returns (e.g. a new expiry date), which is the one remaining gap for an agent scripting the renewal.

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% and the schema already says '4-digit verification token sent via email', so the description's mention of the code and its email origin largely repeats structured data. It adds the human-obtains-it workflow detail but no format or error-handling nuance 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?

States a specific verb and resource ('Das Konto ... verlaengern') along with the required 4-digit code and the lifecycle cadence (alle 3 Monate). It explicitly distinguishes itself from the two nearest siblings, login and register, so an agent can route without ambiguity.

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?

Gives explicit triggers ('wenn eine Verlaengerungsaufforderung kommt oder die Laufzeit auslaeuft') and explicit exclusions with alternatives ('Zur Erstanmeldung: login', 'Ein neues Konto entsteht hier nicht: dafuer register'). Both when-to-use and when-not-to-use are covered.

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