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edit_level_instance

DestructiveIdempotent

Enter in-place edit mode on an ALevelInstance to modify its actors: unloads the instanced sub-level and reloads it as an editable streaming level. Close with commit_level_instance.

Instructions

Enters in-place edit mode on an ALevelInstance: the engine unloads the instanced sub-level and re-loads it as an editable streaming level so its actors can be modified in the current editor world, then closed by commit_level_instance. Canonical headless path: resolve the ALevelInstance by label/name, then ULevelInstanceSubsystem::CanEditLevelInstance (gate) -> EditLevelInstance. CanEditLevelInstance is checked BEFORE EditLevelInstance on purpose: EditLevelInstanceInternal opens with check(CanEditLevelInstance(LI)) — a HARD ASSERT — so this ordering turns an un-editable instance into an honest error (with the engine's Reason) instead of a crash. Idempotent: an instance already in edit mode is a no-op (already_editing:true, editing:true). DEFENSIVE CRASH GUARD: on a World-Partitioned map the edit path calls FModuleManager::GetModuleChecked("LevelInstanceEditor") which asserts if that module is not loaded; when the world is partitioned AND the LevelInstanceEditor module is not loaded we fail honestly instead of proceeding. (create_level_instance produces non-partitioned maps, so the normal flow passes this guard.) Requires the editor (GEditor); EditLevelInstance touches GEditor->Trans / selection unguarded. The edit resets the undo stack and streams the world asynchronously (deferred world-swap), so the edit MUST be closed by a matching commit_level_instance.

Returns: { actor_name: string, editing: bool, already_editing: bool, note: string }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
actor_nameYesRequired. Label or name of the ALevelInstance actor to open for edit (matched via GetActorNameOrLabel).

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.1.0

TDQS

A4.6/5.0
Behavior5/5

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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description earns credit by explaining WHY: undo stack reset, asynchronous world-swap, sub-level unload/reload, the GEditor requirement, and two named crash guards (assert on un-editable instance, LevelInstanceEditor module on partitioned maps). This is far beyond what the structured fields convey.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action, and nearly every sentence carries operative detail for a destructive, crash-prone operation. It is dense and parenthetical-heavy, with a few asides (e.g. the create_level_instance note) that could be trimmed, so not a clean 5.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, yet the description supplies the return shape (actor_name, editing, already_editing, note) along with the preconditions and failure modes an agent needs to call a complex editor-mode mutation safely. Nothing material is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and there is only one parameter, so the schema already documents actor_name and its GetActorNameOrLabel matching. The description's 'resolve the ALevelInstance by label/name' adds nothing new, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Enters in-place edit mode on an ALevelInstance') and immediately names the sibling that closes it (commit_level_instance), so an agent can distinguish this from commit/create/break_level_instance without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit canonical path (resolve by label/name -> CanEditLevelInstance gate -> EditLevelInstance), names the required closing call, and states the no-op case (already in edit mode). It even explains why the gate precedes the edit, which is actionable ordering guidance rather than mere description.

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

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