create_level_instance

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

Goes well beyond the annotations: discloses the exact API path, that the .umap is validated before binding so no actor is left with a broken WorldAsset, that the sub-level streams in deferred/async so loaded is always false, and that an existing instance at the same location/path returns already_exists=true. This is the rare description that fully explains the mutation's behavioral profile.

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?

Front-loads the action and then moves through constraints, idempotency, and returns in a logical order. Slightly heavy with internal type names (SpawnActor<ALevelInstance>, ALevelInstance::SetWorldAsset) that an agent does not need to invoke the tool, but every sentence otherwise carries load.

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?

No output schema exists, so the description supplies an explicit Returns block covering actor_name, world_asset_path, world_asset_set/valid, loaded, location, already_exists, and note. Combined with preconditions and async/idempotency semantics, an agent has everything needed to call and interpret the result.

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?

Schema coverage is 100%, so baseline is 3, but the description adds meaning the schema lacks: it states world_asset_path must reference a .umap that already exists on disk, and defines the idempotency key as 'same world asset at the same location', which reframes the location and world_asset_path parameters.

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?

States a precise verb and resource: 'Spawns an ALevelInstance actor in the editor world and binds it to a saved map (.umap)'. An agent knows exactly what is created. It does not name or contrast any sibling tool (e.g. create_streaming_level, spawn_actor), so sibling differentiation is absent, though the internal API contrast is helpful.

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?

Gives clear operational context: the canonical headless-safe path is used instead of the editor-interactive ULevelInstanceSubsystem::CreateLevelInstanceFrom, and states the precondition that the .umap must already exist. It stops short of explicit sibling routing ('use edit_level_instance to change it'), so it is context rather than exclusion guidance.

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