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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description reinforces that nothing is saved, but adds no further behavior such as parse failure modes, whether results are cached, or rate limits; with annotations carrying the load, a 3 is appropriate.

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?

Two tight sentences with the no-save guarantee and the workflow trigger front-loaded; zero filler and nothing redundant.

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 no output schema, the description tellingly names the return payload ('proposed itinerary segments'), which is the key thing an agent needs. It does not detail the structure of those previews or what happens on unparseable input, leaving a small gap.

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 four parameters (text, trip_id, user_hint, max_segments) are already documented in the schema, including the default of 10 and the 1-20 range. The description adds no syntax, format, or semantic detail beyond the schema, 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 and resource ('Parse pasted travel confirmation text') plus the output ('proposed itinerary segments') and the crucial scope qualifier 'without saving anything'. This cleanly separates it from write siblings such as segment_create and batch_segment_create.

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?

'Use this before creating segments from copied email, PDF, or booking text' gives an explicit trigger condition and workflow position. It stops short of naming the alternative tools (e.g., batch_segment_create) or stating when this preview is unnecessary, but the context is unambiguous.

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