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

Annotations already declare readOnly, idempotent, and non-destructive hints. The description adds useful behavioral context: the error behavior when a city is not recognized, the default and range for limit, and the ordering of results. This goes beyond annotations without contradicting them.

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 concise and well-structured: a clear purpose sentence followed by parameter explanations in a standard args format. Every sentence adds value, and the front-loaded purpose ensures quick understanding.

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 two-parameter read-only tool with no output schema, the description adequately explains what is returned (stations, prices for gasoline and diesel, ordering). It does not specify exact field names, but given the tool's simplicity and good annotations, this is sufficient.

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 schema already documents both parameters well. The description repeats this information but adds the detail that invalid city errors include valid examples, which is not in the schema. This is a small increment, so baseline 3 is appropriate.

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 returns gas stations with the best prices in a specific city, ordered from cheapest to most expensive, including gasoline and diesel prices. This is a specific verb+resource combination that distinguishes it from siblings like 'get_country_coverage' and 'get_active_alerts'.

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 clearly implies when to use it (for city-specific fuel price queries) and mentions the city must be covered by EkoPump. However, it does not explicitly state when not to use it or mention alternative tools for broader coverage, though sibling names make this reasonably clear.

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