Open WebUI MCP Server

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

No annotations are provided, so the description carries the full burden. It mentions 'ADMIN ONLY' which hints at authorization needs, but doesn't disclose other behavioral traits like whether this is a destructive operation, what happens on failure, rate limits, or what the output looks like. For a creation tool with zero annotation coverage, this is inadequate.

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 just two phrases, front-loading the core purpose and the critical admin constraint. Every word earns its place with no wasted text.

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 complexity (a creation tool with a nested parameter object), lack of annotations, and the presence of an output schema (which reduces the need to describe returns), the description is incomplete. It misses crucial details like parameter guidance, error conditions, and behavioral context needed for safe and effective use.

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 input schema has 0% description coverage (the schema's properties have descriptions, but the overall schema lacks a description), and the tool description provides no information about parameters. With 1 required parameter ('params') that is a complex nested object, the description fails to add any semantic value beyond what the bare schema provides.

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 action ('Create') and resource ('new custom model wrapper'), making the purpose evident. However, it doesn't differentiate from sibling tools like 'create_function' or 'create_tool' that also create resources, so it doesn't reach the highest score.

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 includes 'ADMIN ONLY' which provides some usage context regarding permissions, but it doesn't explain when to use this tool versus alternatives like 'update_model' or 'get_model', nor does it provide prerequisites or exclusions beyond the admin requirement.

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