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

With readOnlyHint=true already covering safety, the description adds genuinely valuable behavior: 'up to 3 proven routing templates with bookability ratings' informs the agent about result cardinality and quality signals, and 'proven' suggests historical/heuristic data. This enriches the output semantics beyond the Boolean annotations, though it could have elaborated on determinism or result freshness.

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 tightly constructed sentences: the first states the tool's function, the second the output contract, and the third the use case. Every clause earns its place with zero filler or redundancy.

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 read-only suggestion tool with flat, fully-documented parameters and no output schema, the description covers the key bases: purpose, filters, output count, result quality, and intended scenario. It doesn't address pagination or determinism, but given the low complexity and strong annotations, those are minor omissions rather than critical gaps.

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% with rich inline details (e.g., region enums, maxStops recommendation, tripType examples), so the baseline is 3. The description's mention of 'regions, direction, and alliance preference' only restates what the schema already documents, adding no semantic value beyond it.

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 uses a specific verb-resource pairing ('Get suggested multi-stop flight routings') and names the key filters (regions, direction, alliance preference), clearly framing this as an inspiration/suggestion tool. 'Proven routing templates with bookability ratings' plus 'trip planning inspiration' differentiates it from siblings like route_validate or custom_route_build, which imply validation and precise construction respectively.

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?

The phrase 'Great for trip planning inspiration' implies a light-weight, idea-generation use case, and 'suggested' signals this isn't for precise booking. However, there are no explicit 'when not to use' rules or named alternatives among siblings like route_estimate or plan_route, so guidance remains implied rather than explicit.

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