create_users_by_id_lists

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

Annotations already declare readOnlyHint=false and idempotentHint=true, so the agent knows it's a non-destructive write. The description adds no behavioral context beyond that; it only says 'Create personal list' and instructs to read GET/schema for fields, which is more about parameter discovery. No disclosure of side effects, authentication requirements, or reversibility.

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 extremely concise, with a one-line purpose, an endpoint, and two argument descriptions. It front-loads the purpose and then gives technical details. Every sentence is minimal with no wasted words, though it may be too sparse for a complex operation. Still, it is efficient and structured.

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?

Given that the body parameter is an open object and there are many related list operations, the description is incomplete. It doesn't explain what constitutes a 'personal list' or how it differs from a smart list. It relies on the agent to consult other endpoints for field details, adding friction. It also doesn't mention response format, though an output schema exists. Overall, an agent would need additional research to use this tool correctly.

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 schema describes id and body, but body is an open object with no defined fields. The description adds the guidance to 'Read the matching GET or the /schema endpoint first to see the fields this resource expects.' This helps an agent discover the expected body structure, which is valuable given the schema provides no details. However, it doesn't specify any actual fields, so it's a pointer rather than a full explanation.

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 states a clear verb and resource: 'Create personal list.' It also provides the endpoint POST /users/{id}/lists. The term 'personal list' distinguishes it from smart lists (e.g., create_users_by_id_smart_lists), though it could be more explicit about what a personal list entails. The purpose is clear enough for an agent to understand the action.

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 description offers no guidance on when to use this tool versus alternatives like create_users_by_id_smart_lists or update_users_by_id_lists_by_list_id. It doesn't mention any prerequisites, exclusions, or conditions. An agent has no basis to choose this tool over others in the same domain.

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