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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds meaningful behavior beyond that: per-car-type fixed pricing, inclusion of the Eurotunnel crossing, a no-discount pricing rule, and the fallback return (list of available EU destinations) when a city is unconfigured.

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-loaded with the core purpose, then routing rule, then return/pricing behavior and the fallback path. Dense and mostly waste-free, though the capitalized emphasis and multiple clauses make it longer than strictly necessary.

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 carries the burden of describing returns and does so (per-car-type prices, fixed per vehicle, Eurotunnel included, final prices). It also covers the failure mode and the correct customer-facing response, leaving no obvious gap for correct invocation.

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 car_type, hub_code and destination with their constraints and examples. The description adds only the domain scope for destination (continental city); baseline 3 is appropriate since the schema does the heavy lifting.

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 (get prices) and resource (European/cross-Channel transfer from London/UK to a continental destination), with example cities. It explicitly distinguishes itself from the sibling london_airport_transfer_quote, so an agent can route correctly without opening either schema.

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?

Provides an explicit use condition ('whenever the destination is OUTSIDE the UK / on the European continent') and names the alternative tool to avoid by name. It even covers the edge case of an unconfigured city and what to tell the customer.

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