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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so the safety profile is fully covered by structured data. The description adds no behavioural context of its own: no return shape, no pagination, no explanation of how the optional query affects results.

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?

A single front-loaded sentence with no wasted words. It is efficient, though the trailing 'for the Dover Strait demo' phrase consumes space without clarifying the tool's behaviour.

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 read-only list tool whose annotations carry the safety profile, the description is minimally adequate. However, with no output schema and no explanation of what a 'fuel type' record contains or how the free-form query filters results, an agent still lacks enough to call it confidently.

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% (the free-form 'query' object is documented in the schema), so the baseline of 3 applies. The description never mentions the query parameter, so it contributes nothing beyond what the schema already states.

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 ('List fuel types'), so an agent knows this is a read-only catalogue lookup. It does not, however, distinguish itself from the sibling fuel tools fuel_prices and fuel_full_flow, and the 'Dover Strait demo' qualifier is an unexplained scope limiter.

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?

There is no statement of when to use this tool versus fuel_prices or fuel_full_flow, no prerequisites, and no indication of when it should not be used. The agent is left to infer the choice from names alone.

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