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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description discloses critical behavioral details: results are probability-ranked, not bookable, connection timing is not validated, and verification on the airline's site is required. It also explains the coverage-ratio algorithm and the direct-flights-first rule, which helps the agent set correct expectations.

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?

The description is two compact sentences with high information density. The first sentence front-loads the usage trigger and primary status; the second packs the algorithm, ranking criteria, and output caveats. No 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 tool with 5 parameters and no output schema, the description covers the essential behavior, ranking logic, and limitations. It leaves out the exact result structure and how max_results interacts with appended baselines, but the schema handles parameters and the core planning behavior is well specified.

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 the baseline is 3. The description repeats max_stops defaults but does not add deeper meaning beyond the schema for parameters like date or max_results. It does not need to compensate because the schema already fully documents each parameter.

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 verb ('plan') and resource ('itinerary'), defines the tool as the 'PRIMARY TRAVEL-PLANNING TOOL', and explains its ranking by coverage ratio. It clearly differentiates from sibling tools by focusing on multi-stop itinerary planning and explicitly saying it returns routings, not bookable itineraries.

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 description gives an explicit trigger ('Use when the user asks ...') and positions itself as the primary planning tool, which provides clear context for when to use it. However, it does not name sibling alternatives or state when not to use it, so it stops short of full when/when-not guidance.

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