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

Annotations already declare non-read-only, non-idempotent, non-destructive behavior; the description usefully adds the planner:write auth requirement and the account scope, which the annotations do not cover. It fails to explain the practical consequence of idempotentHint=false (e.g. whether repeated saves duplicate plans) or how itineraryId triggers an update versus a create.

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 short sentences, no padding, with the permission prerequisite front-loaded. Efficient, though the second sentence carries a lot of unelaborated meaning.

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?

An output schema exists so return values need not be described, but with 0% parameter coverage and an unconstrained nested 'plan' object, an agent cannot construct a valid call. Missing are the plan shape, the create-vs-update semantics of itineraryId, and any guidance against sibling planning tools.

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 0% and all three parameters are undocumented in the schema. The description's 'compact day/week plan' is the only hint at the required 'plan' object's shape, and it says nothing about title or itineraryId. With a freeform nested object and zero coverage, the description should compensate but does not.

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 pair ('save or update') and resource ('compact day/week plan') on a defined target ('connected member account'). It distinguishes persistence from generation siblings like plan_day and plan_conference_week only implicitly, and never names an alternative.

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 word 'or update' hints that this is the persistence step after a plan exists, and the permission requirement is stated. But there is no explicit condition for choosing this over plan_day, plan_conference_week, or save_guide_item, and no when-not guidance.

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