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

Annotations already cover read-only, idempotent, non-destructive, closed-world. The description adds value beyond them: it discloses the reprice step and the response contents (total plus Paytm booking link), which the annotations do not. It does not mention latency or pricing-staleness caveats, so it stops short of 5.

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?

Two tight sentences, front-loaded with what it does, then the trigger condition and the not-a-chat-tool boundary. Every clause carries information.

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?

Output schema exists, so return values need not be explained, yet the description still summarizes them usefully. The main gap is provenance of the two offer tokens and any failure/expiry behavior on reprice, which a widget-side tool with rich annotations can afford to omit.

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 0% and neither parameter has a description, but the semantics are largely self-evident from the names and from the description's 'chosen onward + return flight pair' framing. It still never says where these tokens come from, which an agent would need to obtain them.

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?

Specific verb (Computes the combined round-trip fare) plus resource (onward + return flight pair) and scope (reprices, returns total plus booking link). Clearly distinguished from siblings like search_flights or get_fare_family, which handle search and fare families rather than fare combination.

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?

States when it fires: 'Called by the flight search widget when both legs are selected.' The 'not a chat tool' note heads off an obvious misuse, but no alternative tools are named (e.g., fare_calendar or get_fare_family) for related fare questions.

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