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

Annotations already declare this is a non-read-only, non-destructive write, so the safety profile is covered. The description adds genuinely useful behavioral context the annotations lack: a hard quota (up to 20 lists per house) and the fact that the new list coexists with a default list.

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?

Three short sentences, front-loaded with the core action, then the quota, then the return value. Every sentence carries distinct information with no padding.

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 one-parameter write with an output schema, this covers purpose, quota, and the downstream use of the returned id. It stops short of stating behavior when the 20-list cap is reached, which is the only real 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 coverage is 100% and the single required parameter is fully documented, so the schema carries the weight. The description adds example list names but no syntax or constraint detail beyond the schema's 60-character limit.

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+resource ('Create a new named shopping list') plus scope ('for the household'), with concrete examples. It clearly separates itself from list_shopping_lists, update_shopping_list, and delete_shopping_list.

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 implies downstream usage by explaining the returned id is passed as shoppingListId when adding items, which routes the agent toward add_shopping_list_item. However, it gives no explicit when-not-to-use rules or prerequisite here; the duplicate-avoidance guidance lives only in the schema's parameter description.

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