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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add behavioral detail, which it does: up to 5 results returned, the exact result fields, and the non-obvious rule that price:null legs bypass the max_price cap. That null-price edge case is real behavior an agent could not predict from the schema alone.

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?

Three sentences, well front-loaded: purpose and filters first, return shape second, usage context third, with the max_price caveat last. Slightly redundant with the schema's max_price text, but nothing is wasteful.

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 supplies the return fields and the result cap, and it discloses the one surprising behavioral rule (unknown-priced legs included despite max_price). Combined with annotations covering safety, an agent has everything needed to call and interpret this tool.

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% and every parameter is documented in the schema, including the max_price null-price caveat, which the description largely restates. Baseline 3 is appropriate since the schema carries the parameter burden and the description adds no new syntax or format 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?

States a specific verb and resource (search empty leg flights) plus the exact filter set. The siblings (get_flight, request_booking, booking_handoff, get_charter_estimate) are retrieval or booking tools, so the search-and-filter purpose is unambiguous without opening any schema.

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?

"Use this to find discounted private jet availability for a specific route" implies the context of use, but there is no explicit when-not-to-use, no mention of when to prefer get_flight or get_charter_estimate, and no stated prerequisites. Adequate but leaves routing to inference.

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