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

Annotations already declare the tool as read-only, open-world, idempotent, and non-destructive. The description adds that data is real-time from the MTS-K feed and mentions output fields like open status. It does not disclose potential rate limits, authentication requirements (beyond the optional _apiKey in schema), or any side effects. The description adds some but not extensive behavioral context beyond annotations.

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 efficient: four sentences that front-load the core purpose, then provide essential context (geocode first, Germany only), and end with a concrete example. Every sentence adds value; there is no fluff.

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?

Given the tool's moderate complexity (7 parameters, 2 required, enums, no output schema), the description adequately covers the purpose, prerequisite (geocode), geographic scope, and an example. It mentions output fields and open status. It does not describe the exact output structure (though no output schema exists), and it omits information about the _apiKey parameter in the description (though it's in the schema). Overall, it is sufficiently complete for a read-only tool.

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 coverage is 100%, so the baseline is 3. The description adds an example with concrete values and mentions that radius_km has a default of 5 and maximum of 25 (already in schema). It also implies sort constraints ('sort by price requires a single fuel type'), which is already detailed in the schema. The description does not substantially augment the schema's parameter documentation.

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 clearly states the tool's purpose: finding German gas station fuel prices near a location. It specifies the exact resources (diesel, E5, E10) and output fields (price, brand, address, distance, open status). The purpose is fully distinguished from sibling tools through its focus on nearby stations.

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 provides important usage context: it mentions that coordinates are required, advises geocoding first, and states data covers only Germany. However, it does not explicitly guide when to use this tool versus alternative tankerkoenig tools like tankerkoenig_prices or tankerkoenig_station_details, nor does it specify any exclusion criteria.

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