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

Annotations already cover read-only, idempotent, non-destructive and closed-world, so the description's added value is the availability semantics: the record is 'live' and 'says it is no longer available once booked, withdrawn or flown'. That tells the agent to expect a stale/invalid outcome rather than a hard error — genuine context beyond the structured hints, though it omits what an unavailable result looks like.

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 with zero filler: the identity and lookup key come first, the availability caveat second. Nothing is repeated from the title and 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?

With no output schema the description must hint at the return: it discloses that pricing is party-size dependent and that the leg can report as unavailable. What the response actually contains (fields, aircraft, route) is left unstated, a minor gap for a single-record fetch.

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 100%, so baseline is 3; the description earns a bump by tying 'priced for the party size' to `passengers`, explaining that party size affects the returned price — a causal link the schema does not state. `currency` and the exact ref format remain schema-only.

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 resource ('Re-read one live empty leg') plus the keying mechanism ('by the `ref` a search returned'), which implicitly distinguishes it from search_empty_legs and booking_handoff. It stops short of naming the sibling outright, but an agent can still tell what this does.

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?

Usage is implied rather than stated: 'the `ref` a search returned' tells the agent a prior search is required, and the schema confirms search_empty_legs is the source. There is no explicit when-not guidance or mention of alternatives such as re-running the search instead of re-reading.

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