Open WebUI MCP Server

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

With no annotations provided, the description carries the full burden. It discloses the admin-only requirement, which is crucial behavioral context. However, it lacks details on return format, pagination, or any rate limits, leaving the agent to infer from the output schema alone.

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 front-loaded with the core purpose in the first phrase and adds critical constraint in the second. Every word earns its place, with no redundancy or unnecessary elaboration, making it highly efficient.

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 the tool's simplicity (0 parameters, output schema exists), the description is largely complete. It covers purpose and admin requirement, but could benefit from mentioning the output format or any limitations, though the output schema mitigates this 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?

There are 0 parameters, and schema description coverage is 100%, so the baseline is high. The description adds no parameter-specific information, but this is acceptable given the lack of parameters, maintaining clarity about the tool's zero-input nature.

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 clearly states the specific action ('List all users') and resource ('in Open WebUI'), with no tautology or vagueness. It precisely distinguishes this from sibling tools like 'get_user' (singular) or 'delete_user' (different operation).

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 explicitly states 'ADMIN ONLY', providing clear context about required permissions. However, it does not specify when to use this tool versus alternatives like 'get_user' for individual user details or 'update_user_role' for modifications, leaving some guidance gaps.

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