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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds valuable behavioral context: the address is a mandatory field under § 14 UStG and must not be produced from memory. This goes beyond the annotation and helps the agent use the tool correctly.

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: two sentences that front-load the function and then provide the critical usage rule and legal rationale. No filler or repetition.

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 read-only lookup tool with two well-documented parameters and no output schema, the description is complete. It covers the data source, return value, when to use it, and even the legal reason. An agent has enough information to invoke it correctly.

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 ('limit' and 'suche'), with coverage at 100%. The description does not add parameter-specific semantics beyond what the schema contains, so the baseline score of 3 is appropriate.

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: it searches the account's customer file ('Kundenkartei') and returns the full address. It also ties the tool to a concrete workflow ('VOR jedem rechnung_erstellen'), which clearly distinguishes it from siblings like 'rechnung_erstellen' and 'rechnungen_suchen'.

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 gives explicit usage context: use it before creating an invoice if the recipient has already been supplied. It does not explicitly mention when not to use the tool or name alternative tools, but the condition is clear and actionable.

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