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

Annotations already declare this is a non-readonly, non-idempotent, non-destructive write with closed-world behavior. The description adds meaningful behavioral context beyond that: the saved comparison is private to the signed-in account and cannot be opened by others until share_comparison creates a link.

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 tight sentences with no wasted wording. The core action and privacy constraint are front-loaded, followed by the important sharing condition.

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 private save operation, the description covers the essential behavior, source of plan ids, count limits, and the share_comparison relationship, while annotations cover mutation safety. It is not fully complete because optional parameters such as name and locale are not explained, and no return behavior is described, though there is no output schema to document.

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 low at 33%, so the description should compensate, but it only reinforces the items parameter by saying 2 to 4 plans and naming the source tools. It says nothing about the optional name parameter or locale behavior, leaving those to sparse or missing schema documentation.

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 gives a specific verb and resource: saving 2 to 4 digital plans as a private comparison in the signed-in person's account. It also names the sibling tools that supply plan ids (compare_digital / compare_mobile) and the downstream sharing tool (share_comparison), so an agent can distinguish it from related comparison and sharing tools.

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?

Usage is clearly implied: use this after obtaining plan ids from compare_digital or compare_mobile, and use share_comparison later to create a link. The description does not state explicit exclusions or contrast with alternatives like list_my_comparisons, so it is strong context but not complete 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.