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

Annotations only declare write/non-idempotent/non-destructive, but the description adds substantial behavior: per-item partial success/failure with index-based failure reporting, the 50-segment cap, date-range auto-extension with a warning, place-linking side effects (map pin, coordinates, and auto-filled name/address/phone/website), and the 'time not set' semantics. This is far richer than the annotations 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?

Long, but front-loaded with the core action and then ordered by importance: batching, partial-failure handling, limits, date rules, place linking, time rules. Nearly every sentence carries actionable constraint, though the density is dense enough that a tighter grouping would help.

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 batch write tool with no output schema, the description supplies the missing return behavior (failed items returned by index with reasons) and covers prerequisites, limits, and edge-case date handling. An agent has everything needed to call it correctly.

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 100%, so the baseline is 3, but the description earns extra by cross-referencing segment_get_schema for field naming, defining the Activity activityType values, and specifying startDateTime formats (YYYY-MM-DD vs. clock time) plus the placeId contract that the generic 'fields' object does not document.

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 ('Create multiple segments in a trip in one call'), immediately distinguishing the batch operation from the single-item segment_create sibling. An agent knows exactly what this does without opening the 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?

Explicit when-to-use and when-to-escalate: split itineraries larger than 50 segments, resend only failed items, call trip_update for dates more than 1 day outside the trip, and call places_search before creating Activity/Lodging/EventTicket/Parking at a real place. Alternatives and preconditions are named, not inferred.

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