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

With no annotations, the description carries the full burden and does well: it discloses that price and impressions are authoritative from the stored quote and that conflicting inputs are ignored, plus the idempotency behavior for retries. It omits auth requirements and whether the call actually charges money (the Stripe checkout URL implies a later payment step but this is left implicit).

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?

Four tight sentences, front-loaded with the action and followed by the authoritative-price rule, the return value, and the retry hint. Every sentence carries distinct information; there is no padding, though the opening 'Book a flight' phrasing costs a small amount of clarity.

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 16-parameter mutation tool with no annotations and no output schema, the description supplies the essential missing context: the dependency on estimate_ad_cost, the override-ignored rule, the return values (order_id + Stripe checkout URL), and the idempotency contract. Format-specific parameter requirements (music slots, display creatives) are left to the schema, which is reasonable given their full coverage.

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 per-parameter meaning is already documented and the baseline is 3. The description adds cross-cutting semantics the schema cannot: that quote-derived values override submitted ones, and the retry contract for idempotency_key.

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 gives a specific verb+resource ('Book a flight ... with creative assets') and explicitly ties itself to the quote flow, naming the sibling tool estimate_ad_cost as the source of quote_id. The main ambiguity is the mismatch between the tool name (create_ad_order) and the phrase 'book a flight', which an agent may briefly misread before the 'Returns an order_id and a Stripe checkout URL' clause clarifies the resource.

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?

It prescribes the correct sequence (obtain quote_id from estimate_ad_cost, then book) and explicitly recommends idempotency_key for safe retries, which is actionable guidance. It stops short of naming when NOT to use it (e.g. vs create_checkout_session) or stating prerequisites such as authentication or quote expiry.

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