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

The annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds genuinely useful context beyond those: the data is a researched table rather than live inventory, prices are estimates carrying an as_of date, and dynamic programs will vary. It does not discuss coverage gaps, empty results, or lookup failures, which keeps it at 4.

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 compact sentences: what it returns first, when to use it second, and the reliability caveat last. Every clause carries information and nothing is repeated from the title or schema.

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 usefully sketches the return content (per-program prices, sweet spots, as_of date). All three required parameters are addressed. The one remaining gap is that 'programs' takes free-form slugs with no indication of where valid slugs come from, which an agent would need to discover elsewhere.

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 67%, with market and programs carrying helpful inline descriptions and cabin being a self-explanatory enum. The description's main semantic contribution is the 'one-way' unit qualifier, which matters for interpreting prices. It adds little on parameter syntax or valid program slugs beyond what the schema already provides, so the baseline 3 is right.

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 resource and scope: 'Typical saver award prices (one-way) by program, market and cabin from a researched table, plus known sweet spots.' That is far more informative than the title 'Award prices' and separates it conceptually from siblings like points_value or transfer_options. It stops short of explicitly naming or contrasting a sibling, so it is a clear 4 rather than a 5.

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 gives three concrete usage conditions: when live award search is unavailable, to shortlist programs, and to judge whether a live price is good. That is strong when-to-use guidance, but there is no explicit when-not or named alternative tool (e.g., a live search tool or points_value), so it does not reach the 5 level.

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