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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so safety is covered. The description adds real behavioral context beyond them: bulk batching up to 10 ids, real-time MTS-K sourcing, and a hard geographic restriction (Germany only). It does not mention rate limits, error behavior for invalid ids, or partial-result handling, so it stops short of a 5.

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-loads the core purpose, then usage context, then an example in three tight sentences with no filler. The example duplicates the schema's examples block slightly, which is minor redundancy rather than bloat.

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?

With no output schema, the description usefully names the returned measures and units (E5/E10/diesel, EUR per liter), and it covers scope, precondition, and data source. Only minor gaps remain (error/partial-failure handling), which is acceptable for a read-only batch lookup.

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%, so the schema already documents both station_ids (1-10 UUIDs from tankerkoenig_stations_nearby) and _apiKey. The description reinforces the 'up to 10' cap and supplies a concrete invocation example, but adds no new format or constraint semantics, so the baseline 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 and resource ('bulk current fuel prices'), the exact fields returned (E5, E10, diesel in EUR per liter), and the scope (up to 10 German stations by id). This is clearly distinguishable from the sibling tools tankerkoenig_stations_nearby (discovery) and tankerkoenig_station_details (single-station lookup).

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 frames itself as 'the efficient refresh call for price-watch and price-alert flows once station ids are known', which tells the agent the precondition (ids must exist) and the use case. It points to tankerkoenig_stations_nearby as the id source via the schema, but does not state an explicit when-not-to-use or name the alternative in the description text itself.

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