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

Beyond the annotations (readOnlyHint=false, idempotentHint=true), the description adds that the call 'blocks the day' and that 'retrying with the same key never creates a second booking', elaborating on the idempotency guarantee. It also discloses the return of 'the booking reference and an access code'.

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 three sentences, front-loaded with the core action, and each sentence adds essential information (action, condition, requirement, return). No redundant phrases.

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 25-parameter tool with an output schema, the description covers the critical gating and side-effect information. It does not explain all required fields, but the schema already documents many, and the description focuses on the conditions that are easy to get wrong. The main gap is lack of guidance on which parameters are mutually exclusive or required only for airport pickups, but that is partially in the schema.

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 52%, so the description should compensate for under-documented parameters. The description highlights quote_id, customer_confirmed, accepted_terms, and idempotency_key but does not add meaning to the many unannotated parameters like first_name, last_name, or pickup_address. The idempotency_key explanation adds value, but overall the description adds minimal parameter-level detail.

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 states a specific action: 'Creates a REAL, CONFIRMED booking in RIED.TAXI's booking system and blocks the day.' This clearly differentiates from siblings like get/cancel/update/hold by emphasizing the confirmed creation action and its side effect.

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 gives an explicit condition: 'Only call after the customer has seen the complete trip and price and explicitly said yes.' It also lists required prerequisites (quote_id, customer_confirmed, accepted_terms, idempotency_key), but it does not explicitly name sibling tools or state when to prefer an alternative such as hold_booking.

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