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

Annotations declare readOnlyHint=true and idempotentHint=true; the description is consistent with that and reinforces it ('Nothing is booked or charged by this tool'). It goes further by describing the downstream confirmation and payment flow, which annotations cannot express. It omits link validity/expiry, which would be the remaining behavioral gap.

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 and the no-booking disclaimer, and the place list is operationally useful. The closing sentence restating the airport naming slightly duplicates the place list, so it is not wasteful but not perfectly tight either.

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 an 8-parameter tool with no output schema, the description covers what it produces (a prefilled booking link), what it does not do (no booking, no charge), and the valid place vocabulary. An agent has everything needed to call it and to set caller expectations.

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 88%, so the baseline is 3, but the description adds genuine meaning by enumerating known place values for from/to and fixing the exact naming for the two airports. That directly reduces invalid-value calls beyond what the schema enumerates.

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 artifact ('Builds a link ... with the request already filled in') plus the exact fields prefilled. It is clearly distinguishable from the read-only siblings get_service_info, get_transfer_price, and list_routes.

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 conveys the workflow context (traveller reviews, sends via WhatsApp, confirmation happens in chat, payment after the ride), which tells the agent where this tool sits in the process. It never explicitly names a sibling or states when NOT to use it, so it stops short of full routing guidance.

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