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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description's "Rein lesend" is redundant with the annotations; its only added context is the account-scoping (only the logged-in user's favorites are returned). No pagination or result-shape detail is given, so a 3 is appropriate.

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?

Front-loaded with the core action, then alternatives, then a short English keyword tail ("favorite, bookmark, quick access") that aids discovery. Slightly dense with three sibling references, but every sentence carries routing value.

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 zero-param, read-only list tool with no output schema, the description covers purpose, scope, safety, and alternatives adequately. It could say a bit more about what a favorite entry contains, but nothing needed for correct invocation is missing.

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 tool takes zero parameters, so there is no parameter semantics to explain and the baseline is 4. The description correctly implies no filtering arguments are required.

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 ("Die eigenen Favoriten auflisten") plus scope (gemerkte Objekte des angemeldeten Kontos), and explicitly names the adjacent siblings onto_favorite_add, onto_favorite_delete, and onto_object_index. An agent can distinguish this from the toggle/add/delete/index siblings without opening any 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?

Gives explicit routing: use onto_favorite_add to bookmark, onto_favorite_delete to remove, and onto_object_index for all objects rather than favorites. The when-to-use intent ("schnell auf haeufig gebrauchte Objekte zuzugreifen") is also stated, leaving nothing to inference.

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