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

Annotations already declare this as a read-only, idempotent, non-destructive operation, so the safety profile is covered by structured data. The description adds only the output summary (total cost and liters used), which is largely duplicated by the existing output schema, and says nothing about rounding, currency handling, or units of the result.

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 purpose, then use case, inputs, output, and a cross-reference in four short sentences with little waste. The inputs sentence is somewhat redundant with the schema, but the overall shape is tight.

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 pure deterministic calculator with full annotations, a 100%-covered schema, and an output schema, the description supplies enough framing (purpose, use case, inputs, related bundle). It omits only minor things like rounding/currency assumptions of the returned cost.

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 all three parameters with units. The description restates the same inputs with the same units, adding no meaning beyond the schema descriptions (e.g., no note on acceptable ranges or what consumption means for the result).

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 ('Compute fuel cost for a journey'), so it is unambiguous against the many sibling calculators. It does not, however, explicitly distinguish itself from the closest sibling calculate_fuel_consumption, which is the main ambiguity an agent would face.

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?

Gives concrete use contexts ('trip budgeting or company expense') and points to list_bundles for adjacent 'auto-transport' calculators. There are no when-not conditions or an explicit hand-off to a specific alternative tool, but the usage context is clear.

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