UEAgent 1.2.2

A patch release: more calls that killed or hung the editor are refused, the Sequencer tools accept either spelling of their sequence, and a no-op no longer saves.

Fixed

• Calls that killed or hung the editor are refused before they touch anything:
  copy_dynamic_mesh_to_static_mesh with lod_index 8 or more, a huge section_index on the procedural
  mesh tools or element_index on set_procedural_mesh_material, a procedural grid past 1,000,000
  vertices, a huge option_index on the EQS tools, and duplicate_anim_sequence onto an existing asset.
• Ten Sequencer tools refused a call with only sequence_path or only sequence_name: they published
  both as required. Either spelling works now (add_shot_track, add_subsequence_track,
  add_camera_cut_section, get_sequence_track_count and six more).
• A valid no-op succeeds without saving: the IK Rig, retargeter and animation tools saved on a no-op,
  so during Play-in-Editor or under a read-only root a no-op failed.
• Montage slots: create_anim_montage, add_montage_segment and add_montage_slot added duplicate
  empty DefaultSlot tracks.
• Wrong answers: is_bvh_valid_for_mesh always answered false; reimport_anim_sequence,
  rename_pose_in_pose_asset and set_pose_asset_base_pose answered success for a refusal;
  add_subsequence_track used a cinematic shot track; the track counts left out the camera cut and
  binding tracks; get_niagara_data_interfaces reported object names instead of parameter names.
• Undo for connect_ik_goal_to_solver, set_retargeter_op_settings and the blend space setters.

The full list is in the changelog.

Measured on 172 tool calls in a headless editor: all 172 answer as expected, the 125 that 1.2.1 already
passed included; on 1.2.1 five of the 47 new calls killed or hung the editor.

Install

1. Download UEAgent-1.2.2-UE5.8-Win64.zip and unzip it into <YourProject>/Plugins/, replacing
   an older Plugins/UEAgent.
2. Open the project with Unreal Engine 5.8 on Windows. The plugin is precompiled: no compiler is
   needed, in a Blueprint-only project or a C++ one. The status bar shows MCP · 55561.
3. Connect your client: see Clients.

Files

File
UEAgent-1.2.2-UE5.8-Win64.zip	The plugin, built for Unreal Engine 5.8 (Win64), with its source.
UEAgent-1.2.2-UE5.8-Win64-symbols.zip	Debug symbols (.pdb). Only needed for readable crash call stacks: unzip it over the plugin.
SHA256SUMS.txt	SHA-256 of both archives.

UEAgent is released under the MIT License.

UEAgent 1.2.1

A patch release: calls that killed the editor are refused, and tools that answered success for nothing now say what happened.

Fixed

• Calls that killed the editor are refused before they touch anything: a negative section_index on the
  procedural mesh tools, remap_material_ids with compact: true, a negative option_index on
  add_eqs_test and add_eqs_generator, add_spring_arm and add_camera_component with the name of an
  existing component (they now take a free name), set_anim_frame_rate with an fps that rounds to 0,
  move_ik_solver_in_stack past the end of the stack, and add_skeletal_mesh_socket copying to the
  skeleton of a mesh without one.
• Answers that said success for nothing: set_anim_curve_keys on a transform curve,
  add_anim_bone_track and set_anim_bone_track_keys with an unknown bone (they wrote the root track),
  generate_mesh_uvs (it deleted the UV channels above the one it wrote), apply_uniform_remesh (it could
  not use uv_preserving), set_anim_frame_rate and set_anim_number_of_frames (wrong read-back), the
  dynamic mesh and render target tools, the MetaSound graph input and output tools, the Niagara data
  interface tools, add_mass_trait, add_widget_to_blueprint, remove_string_table_entry, the material
  instance parameter tools, the USD specifier tools, and the stop tools of behavior trees, level sequences
  and widget animations.
• Saves that failed in silence now fail the call with save_error: the Sequencer, animation sequence,
  IK rig and retargeter, Gameplay Cameras, Chooser, geometry collection and Interchange pipeline tools.
• Edits that were lost or half written: the Niagara data interface tools, the set_game_mode_* setters,
  the gameplay effect and cue setters during Play-in-Editor, create_level_sequence on an existing
  sequence, and create_audio_bus / create_sound_source_bus on an existing asset.
• Undo for the smart object slot tools, the EQS, spring arm and camera component tools, the Gameplay
  Cameras setters, the IK settings and retarget pose setters, the Chooser tools,
  remove_niagara_data_interface and set_control_bus_mix_stage_value.
• Documented no-ops that answered failure now succeed (remove_marked_frame, clear_marked_frames, the
  sequence folder tools, add_notify_track).
• setup_foot_ik binds the legs, remove_widget reaches the widgets created in Play-in-Editor, and more:
  see the changelog.

Measured on 125 tool calls in a headless editor: with 1.2.0, 11 of them kill the editor and 95 answer
wrong; with 1.2.1 all 125 answer as expected.

Schema changes

interp_mode of set_anim_curve_interp_mode and rotation of rotate_dynamic_mesh are required (the
tools already refused a call without them); duration_seconds of set_gameplay_effect_duration is optional
(only HasDuration needs it); the six tag lists of set_gameplay_effect_component_target_tag_requirements
are arrays; remove_widget takes an optional target_world.

Install

1. Download UEAgent-1.2.1-UE5.8-Win64.zip and unzip it into <YourProject>/Plugins/, replacing
   an older Plugins/UEAgent.
2. Open the project with Unreal Engine 5.8 on Windows. The plugin is precompiled: no compiler is
   needed, in a Blueprint-only project or a C++ one. The status bar shows MCP · 55561.
3. Connect your client: see Clients.

Files

File
UEAgent-1.2.1-UE5.8-Win64.zip	The plugin, built for Unreal Engine 5.8 (Win64), with its source.
UEAgent-1.2.1-UE5.8-Win64-symbols.zip	Debug symbols (.pdb). Only needed for readable crash call stacks: unzip it over the plugin.
SHA256SUMS.txt	SHA-256 of both archives.

UEAgent is released under the MIT License.

UEAgent 1.2.0

Every tool now says whether it reads or writes and what it answers, 533 tool definitions were rewritten
from their code, and tools that answered success for a failure now say what happened.

What's new

• Tool annotations. Every tool publishes readOnlyHint, destructiveHint, idempotentHint and
  openWorldHint, derived from the code it runs: 640 tools are read-only, 403 additive and 1054
  destructive, and only execute_python and execute_python_file reach outside the editor. A client
  can tell get_blueprint_info from delete_asset without reading the prose, and a reader that
  saves, compiles or writes a file is not marked read-only.
• Return shapes. Every description ends with what the tool answers (Returns: { ... }), in
  tools/list and in describe_tool.
• 533 tool definitions rewritten from their code: what each tool reads or changes, its side
  effects, what a wrong input does and which sibling tool to use instead. About 100 described
  something the code does not do and now match it.
• A Claude Code plugin, ueagent: /plugin install ueagent --marketplace CarlxsMG/UEAgent adds
  skill-builder, which turns an editor workflow into a new skill, and three skills made with it
  (blueprint-actor, project-audit, level-lighting).
• Schemas that say what the code requires: the required and optional parameters and the types of
  112 tools now match their handlers, and a call that passes either spelling of a parameter the tool
  reads under two names reaches the tool (53 tools).

Fixed

• 42 tools answered success for a failure or a no-op. Among them, delete_asset and
  delete_level_sequence fail when the file stays on disk, the Chaos fracture tools count the pieces
  they add, and the Enhanced Input, Soundfield and GAS tools fail when their save fails.
• reimport_anim_sequence reimported the wrong source and could open dialogs;
  validate_anim_state_machine and get_anim_state_machine_info counted transitions as states;
  list_usd_prims ignored recursive; create_attribute_set_asset and add_attribute_to_set left
  every default at 0; remove_tree_binding always failed; set_tree_parameter failed on text;
  configure_ai_sight_radius ignored lose_sight_radius; list_engine_ini_sections found no
  sections.

The full list is in the changelog.

Install

1. Download UEAgent-1.2.0-UE5.8-Win64.zip and unzip it into <YourProject>/Plugins/, replacing
   an older Plugins/UEAgent.
2. Open the project with Unreal Engine 5.8 on Windows. The plugin is precompiled: no compiler is
   needed, in a Blueprint-only project or a C++ one. The status bar shows MCP · 55561.
3. Connect your client: see Clients.

Files

File
UEAgent-1.2.0-UE5.8-Win64.zip	The plugin, built for Unreal Engine 5.8 (Win64), with its source.
UEAgent-1.2.0-UE5.8-Win64-symbols.zip	Debug symbols (.pdb). Only needed for readable crash call stacks: unzip it over the plugin.
SHA256SUMS.txt	SHA-256 of both archives.

UEAgent is released under the MIT License.

UEAgent 1.1.0

Every tool call can now be undone with Ctrl+Z, an Activity panel shows what the agents did, and the
undo tools read the editor's history the right way round.

What's new

• One undo step per call. Each tool call is a single entry in the editor's undo history, named
  after the tool ("UEAgent: spawn_actor"): Ctrl+Z reverts it, and a batch as a whole.
  mcp.UndoStepPerCall 0 in the editor console turns it off.
• Activity panel. Status bar > MCP > Activity lists the last 200 tool calls with their time,
  duration and outcome (OK, a readback warning, failed or refused). mcp.activity prints them to the log.
• Instructions for every agent. initialize tells the agent how to read a readback verdict and a
  refusal, and when to use batch, in the full tool list as well as the compact one.
• The plugin's icon in the editor's Plugins window.

Fixed

• The undo tools read the editor's undo buffer backwards: get_undo_state swapped the undo and redo
  counts, get_transaction_history reported every entry as undone, and the labels of can_undo,
  can_redo and get_undo_state came back empty.

Install

1. Download UEAgent-1.1.0-UE5.8-Win64.zip and unzip it into <YourProject>/Plugins/, replacing
   an older Plugins/UEAgent.
2. Open the project with Unreal Engine 5.8 on Windows. The plugin is precompiled: no compiler is
   needed, in a Blueprint-only project or a C++ one. The status bar shows MCP · 55561.
3. Connect your client: see Clients.

The documentation is now also a website, with search: carlxsmg.github.io/UEAgent.

Files

File
UEAgent-1.1.0-UE5.8-Win64.zip	The plugin, built for Unreal Engine 5.8 (Win64), with its source.
UEAgent-1.1.0-UE5.8-Win64-symbols.zip	Debug symbols (.pdb). Only needed for readable crash call stacks: unzip it over the plugin.
SHA256SUMS.txt	SHA-256 of both archives.

UEAgent is released under the MIT License.

UEAgent 1.0.0

The first public release of UEAgent: an MCP server inside the Unreal Editor, with more than 2,000 tools
in 55 domains and a contract around every call.

Install

1. Download UEAgent-1.0.0-UE5.8-Win64.zip and unzip it into <YourProject>/Plugins/, so the plugin
   ends up in Plugins/UEAgent.

2. Open the project with Unreal Engine 5.8 on Windows. The plugin is precompiled: no compiler is
   needed, in a Blueprint-only project or a C++ one. The status bar shows MCP · 55561.

3. Connect Claude Code from that status-bar menu, or run:

   claude mcp add --transport http unreal http://127.0.0.1:55561/mcp
   

   For Cursor, VS Code, Windsurf, Claude Desktop, Gemini CLI or Codex, see
   Clients.

What is in it

• An MCP server inside the editor (Streamable HTTP on 127.0.0.1:55561), with more than 2,000 tools:
  see the tool reference.
• A contract around every call: preconditions refuse the calls known to crash or freeze the editor,
  and readback re-reads the state after each call.
• Several agents can share one editor.
• A compact tool list for clients that cap how many tools a server may list: find_tools,
  describe_tool and call_tool reach the whole catalog. Connect such a client to
  http://127.0.0.1:55561/mcp?tools=compact.
• Read Only Content Roots: content no tool may save, rename, move or delete.

Files

File
UEAgent-1.0.0-UE5.8-Win64.zip	The plugin, built for Unreal Engine 5.8 (Win64), with its source.
UEAgent-1.0.0-UE5.8-Win64-symbols.zip	Debug symbols (.pdb). Only needed for readable crash call stacks: unzip it over the plugin.
SHA256SUMS.txt	SHA-256 of both archives.

UEAgent is released under the MIT License.