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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: first-time sign-in with a client authorization prompt, and that 'days planned' can be fewer than the date span because the app materializes days lazily. It stops short of saying what happens when the traveller is not signed in or whether the list is ever truncated.

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?

It is front-loaded with the resource and keeps to two sentences with no filler. The middle sentence is a long run-on field enumeration, but each parenthetical (days vs. date span, seq as version) carries real information, so little could be cut without loss.

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?

With no output schema and zero parameters, the description does the necessary work of describing the return fields, their versioning semantics, and the auth prerequisite. The remaining gap is failure/empty-state behavior and whether the result set is complete or filtered by recency.

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?

The tool takes no parameters, so the baseline is 4. The description instead spends its detail on the response fields (id, seq, ingested status, last change), which is the useful place to add meaning given the absence of an output schema.

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 names a specific verb and resource ('the signed-in traveller's trip plans') scoped to the Meridian Dispatch app, then enumerates the returned fields, so the agent knows exactly what the tool yields. It also distinguishes itself from get_plan, which returns a single plan's days and places.

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?

It explicitly routes the agent to get_plan when a single plan's days and places are needed, which resolves the main ambiguity among the siblings. It gives no explicit when-not guidance for the other plan-related siblings (create_plan, edit_plan, delete_plan), though those are distinguished by obvious mutation semantics.

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