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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safe, non-mutating profile is covered structurally. The description adds real operational context beyond that by naming the analyses it runs (dead legs, poison carriers, bookability), though it says nothing about cost, latency, or what the warning output 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?

Three sentences with no filler, front-loaded with the core action and followed by the specific checks and the usage cue. Every sentence carries distinct information and nothing repeats 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?

For a read-only validation tool with no output schema, the description covers purpose, checks performed and workflow placement adequately. It stops short of describing the shape of the feasibility result or warnings, which is the only remaining gap given no output schema exists to carry that.

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%, so all three parameters (cities, alliance, carriers) are already documented in the schema with formats and examples. The description adds no additional parameter meaning such as ordering requirements tying carriers to legs, so the baseline 3 applies.

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 (validate) plus resource (multi-city flight routing for feasibility) and enumerates the concrete checks performed: alliance carrier rules, dead legs, poison carriers, bookability. It does not name any sibling explicitly, so an agent must infer the distinction from 'before building an itinerary' rather than a direct contrast with custom_route_build or plan_route.

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?

Gives clear sequencing guidance: 'Use this before building an itinerary to catch routing problems early,' which tells the agent when in the workflow to call it. It offers no explicit when-not condition and never names an alternative tool to use instead, so the guidance is contextual rather than routing.

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