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

Annotations already declare readOnlyHint and openWorldHint. The description adds valuable context: the price is fetched live from the courier and valid for about 15 minutes, which is time-sensitive behavior beyond the annotations. It also reinforces the no-side-effect nature. No contradiction.

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?

Three sentences, each earning its place: purpose, live/validity behavior, and explicit workflow instruction. The description is front-loaded with the core action and contains no filler.

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 one-parameter read-only tool with no output schema, the description covers purpose, side-effect-free behavior, price validity, and the exact call sequence relative to create_cart. The only minor gap is that the return format is not explicitly described, but 'Preis anfragen' makes the returned value inferable.

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 description coverage is 100% for the single 'address' parameter, which already includes a full example. The description does not add parameter-specific detail beyond the workflow context, so the baseline of 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?

States a specific verb ('Fragt den Preis an') with a clear resource (Express-Lieferung per Kurier) and explicitly disclaims side effects ('ohne etwas anzulegen'), distinguishing it from create_cart. It is non-tautological and immediately clear what the 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?

Provides explicit when-to-use guidance: 'Vor create_cart mit express: true aufrufen' and explains the pricing context (normal delivery free, express costs extra). It names the exact adjacent workflow, leaving no ambiguity about the calling sequence.

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