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

Goes well beyond the annotations by disclosing the toggle side-effect (existing entry is DELETED, otherwise created) and that a second call reverses the first — crucial for a tool annotated idempotentHint=false, destructiveHint=false. It does not state permission/auth requirements, but the annotations already rule out open-world reads. The deletion of a bookmark entry is arguably at odds with destructiveHint=false, though it is self-reversing, so this is a tension rather than a flat 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?

Front-loaded with the action, then the critical warning, then routing to siblings. Slightly long and mixes German with a trailing EN keyword line, but every sentence carries actionable information.

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 covers the mutation semantics, reversibility, account scoping, and sibling alternatives — everything an agent needs to invoke it correctly without a pre-read.

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% and both parameters are documented in the schema, so the baseline is 3. The description adds only implicit context (same URL toggles back) rather than new parameter-level semantics.

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 ('Favoriten-Status eines Objekts umschalten') with the toggle direction spelled out (merken <-> nicht gemerkt) and the account scope. It is immediately distinguishable from the sibling onto_favorite_add / onto_favorite_delete, which are named.

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?

Explicitly states when to prefer this tool ('Nutze es, wenn du den Ausgangszustand nicht kennst — du brauchst dann kein Vorab-Lesen') and names both alternatives for the directed cases (onto_favorite_add, onto_favorite_delete). When/when-not/alternatives are all covered.

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