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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint. The description adds value by specifying the return fields ('id, name, summary, image, link, createdAt, updatedAt') and the slim catalog-card nature, giving the agent a concrete expectation of output shape beyond what annotations provide. It doesn't contradict annotations.

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?

Two sentences, each earning its place. The first sentence states purpose and scope; the second lists return fields and points to the sibling tool. Fully front-loaded, no filler or redundancy.

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 no-parameter list operation with an output schema already present, the description covers the essential context: scope of access, return field summary, and the escape hatch to get full details. An agent can call it correctly without further info. The description is thorough given the tool's simplicity.

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 tool has zero parameters, so the description has no parameter details to add. Per baseline, a 0-param tool gets a 4. The description correctly avoids inventing parameter notes and focuses on behavior.

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 specific verb ('List') and resource ('worlds'), and clearly scopes it to 'owns or has access to via membership.' It also distinguishes itself from imagine_get_world, which reads a specific world's full body, so an agent knows this is a catalog listing 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 tells the agent when to use this over an alternative: 'To read a specific world's full body and configuration, call imagine_get_world with the id.' This is a clear routing statement. It also implicitly communicates the use case of listing all accessible worlds without needing parameters.

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