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

Annotations already indicate this is a non-read-only, non-idempotent mutation, and the description adds that the world is owned by the calling user and that fields pass through to imagine for validation/defaulting. It also discloses a non-obvious data-model behavior: worlds do not carry a ruleset, rulesets live on adventures. No contradiction with 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?

Three tight sentences front-load the action first, then add required/optional fields and one clarifying domain rule. There is no filler and no unnecessary repetition of annotation information.

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?

The description covers ownership, required input, and the world/adventure ruleset relationship, and an output schema exists to explain return values. However, the input schema declares an empty object while the description says `name` is required, leaving an agent with contradictory invocation guidance. It also omits what defaults 'imagine' assigns and any error conditions.

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?

Even though the input schema has zero properties, the description identifies `name` as required and `summary`, `description`, and `link` as additional pass-through fields, which is essential semantic content the schema lacks. It does not provide types or format details, but with 0 schema params this meaningfully exceeds the baseline.

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 first sentence uses a specific verb ('Create') and resource ('new world') and adds ownership ('owned by the calling user'). This distinguishes it from siblings like imagine_create_world_page and imagine_create_adventure by naming the exact resource being created. The final sentence further clarifies the world-vs-adventure model.

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 states what the tool does and gives a structural hint that adventures live under worlds, which helps sequencing. However, it never explicitly says when to prefer this tool over imagine_create_adventure or imagine_create_world_page, and it gives no exclusions or prerequisites beyond the required name.

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