Kiro Unity Accelerator

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Note on language availability: README files are available in 5 languages to support our global community. Examples and demo steps are intentionally parallel across all language versions for consistency — each version is human-reviewed for natural phrasing in that language. Steering files (domain knowledge) are in Traditional Chinese with English summary sections at the top of each file. The Power responds in the developer's preferred language, even though steering files are in Traditional Chinese with English summaries. If you encounter any language barriers, please open an issue for community support.

Transform your IDE into a Unity development AI assistant. Use natural language to command Unity Editor via MCP (Model Context Protocol — a standardized way for AI assistants to interact with development tools, allowing developers to describe what they want in plain language instead of manually navigating menus or writing boilerplate scripts). This Power covers asset management, scene building, build automation, performance analysis, code quality checks, and more — with 40+ TypeScript tool modules and 15 domain knowledge files.

Unity 6.4 baseline: This Power targets Unity 6.4 (release stream 6000.4, newest patch 6000.4.12f1, released 17 Jun 2026) and the tool surface of MCP for Unity v10.3.0 or newer (minimum v10.0.0). The minimum Editor for this Power is Unity 6.0 (6000.0); the bridge's own floor is lower (Unity 2021.3 LTS). The guidance was live-checked against Unity 6000.4.6f1 + URP 17.4.0, Windows Editor, 2026-10-21, first on MCP for Unity 9.6.8 and then again on 10.3.0 after the bridge was upgraded on the same machine (see Upgrading the bridge) — Unity 6.5, 6.6 and later 6.x are expected to work but were not verified here. Verified by direct calls on 10.3.0: the running bridge version; the full 49-tool inventory and the fact that the 9.6.8 → 10.3.0 delta is purely additive (6 tools added, none removed or renamed, so the upgrade carries no migration cost for this Power); the new asset_gen tool group, which is off by default and whose tools spend the developer's own third-party credits; all ten tool groups' membership and defaults; and the documented manage_asset / find_gameobjects / manage_scene contracts. A sixth round then exercised the write path on 10.3.0 — GameObject, component, prefab, script and asset-folder mutations, refresh_unity, and run_tests → get_test_job as a complete async job lifecycle — with every write confined to an isolated Assets/_MCPVerify/ folder that was deleted afterwards, the project confirmed back at baseline (see What the write path proved). Still not verified: the six asset_gen tools (deliberately never called — they cost real money), manage_build (blocked by the verification machine's own permission rule), and run_tests against actual tests — the verification project has no test assemblies, so the job lifecycle is confirmed while pass/fail reporting is not. Unity 6.4 is an Update release and its patch stream ended 17 Jun 2026, so a project locking down for production should move to Unity 6.3 LTS (supported through Dec 2027) or forward onto the current Update release. Unity 6.0 LTS support ended 16 Oct 2026 — it is never recommended, not even as a "safe older version". Sources: unity.com/releases and endoflife.date/unity, both retrieved 2026-10-21.

What the 6.4-specific guidance covers: URP Render Graph is the only path — URP Compatibility Mode and the URP_COMPATIBILITY_MODE scripting define were removed in 6.4, so it is no longer an escape hatch for legacy custom render passes; the GPU Resident Drawer (Forward+/Deferred+ GPU instancing, unavailable on the 2D Renderer) together with the redesigned Rendering Statistics window, which itemises which batching path absorbed each draw call instead of reporting one number; InstanceID deprecated in favour of EntityId, so an instance id returned by the bridge is an opaque token — pass it straight back, never do arithmetic on it, sort by it, or parse it; PVRTC removed on iOS (ASTC or ETC only); Web builds running [BurstCompile] jobs on background workers even though multithreaded rendering is still unavailable; a custom render pass can now be injected into the URP 2D frame loop; and the OculusXR package is deprecated in favour of the OpenXR plug-in, with HoloLens 2 support and its plug-in deprecated in 6.4 (the OculusXR removal release is unverified). Scripting backend: manage_build accepts mono or il2cpp only — CoreCLR cannot be selected through this Power. Sources: New in Unity 6.4 and Upgrade to Unity 6.4, both retrieved 2026-10-21.

Rather than trusting a remembered version number, the Power checks the connected project through MCP — manage_graphics(action: "pipeline_get_info") for the active render pipeline, the mcpforunity://project/info resource for the Unity version and platform, and manage_packages(action: "list_packages") for installed packages — before applying any version-specific advice.

Key Concepts: Technical terms used throughout this document (if you are new to Unity development, these concepts will become clearer as you work through the examples — you do not need to understand them all upfront):

• MCP (Model Context Protocol): A standardized protocol for AI assistants to communicate with development tools, enabling developers to use natural language to operate Unity Editor
• DAG (Directed Acyclic Graph): A directed graph with no cycles, used to determine task dependency order (e.g., "import textures before creating materials")
• MVC (Model-View-Controller): An architecture pattern that separates code into data (Model), display (View), and logic (Controller)
• ECS (Entity-Component-System): Unity DOTS data-oriented architecture pattern for efficiently processing large numbers of objects (e.g., managing thousands of entities simultaneously)
• ScriptableObject: Unity's serializable data container for storing configuration and shared data (without needing to attach to scene objects)
• AssetBundle: Unity's asset packaging format for distribution and dynamic loading (reduces initial install size)

Features

• Asset Automation — Batch apply asset presets, auto-detect asset types, generate change summaries
• Scene Scaffolding — One-command scene structure generation with conflict detection
• Build Automation — Local builds through manage_build, build log parsing, reusable build configuration templates
• Cross-Platform Testing — Test execution through run_tests / get_test_job, result formatting, test suite conversion
• Workflow Automation — Multi-step workflows with DAG dependency validation and topological execution
• Performance Analysis — Profiler screenshot analysis, code anti-pattern scanning, optimization recommendations
• Code Quality — MVC/ECS/ScriptableObject architecture checks, circular dependency detection
• Knowledge Management — Team documentation management, API change tracking, staleness detection
• Platform Compatibility — Shader compatibility, memory budget checks, severity classification (including XR/VR)
• Asset Dependency Management — Dependency trees, orphan asset detection, AssetBundle duplication checks
• Level Design Tooling — Editor extension script generation, ScriptableObject templates, batch scene object configuration
• UI Dependency Analysis — Cross-file UI reference tracking, event chain analysis, coupling assessment

Architecture

Developer (Natural Language)
    → AI Layer (Intent Understanding & Planning)
        → MCP Protocol
            → Unity Editor (Execution Layer)

Unity Accelerator (Intelligence Layer)
├── POWER.md        → Main document defining tools & workflows
├── steering/       → 15 domain knowledge files
├── templates/      → Built-in templates (Presets, Scaffolds, Build Configs, etc.)
└── src/            → 40+ TypeScript tool modules

Which "Unity MCP"? — three different projects

Three unrelated projects are called some variant of "Unity MCP". This Power targets only the first one. Mixing them produces tool names and ports that match nothing in this documentation. All three rows retrieved 2026-10-21.

Project	Identity	How it connects	Status
(a) CoplayDev MCP for Unity — what this Power uses	UPM com.coplaydev.unity-mcp, repo CoplayDev/unity-mcp, Python server published on PyPI as mcpforunityserver, MIT-licensed	streamable HTTP (default) at http://127.0.0.1:8080/mcp, or stdio through uvx; the Unity-side bridge also listens on TCP 6400	Active. Verified-current release v10.3.0 (2026-10-04); this Power documents v10.3.0 or newer, minimum v10.0.0. 49 tool entrypoints across 10 groups — counted from a live manage_tools(action: "list_groups") call on 10.3.0, which is the authoritative number (upstream's README says 48)
(b) IvanMurzak/Unity-MCP — a different project, not used here	UPM com.ivanmurzak.unity.mcp, repo IvanMurzak/Unity-MCP	a separate server binary downloaded into Library/mcp-server/; its port is derived from a hash of the project path (range 20000–29999), so there is no port to configure	Active, latest 1.3.0 (~2026-10-20). Its tool names and port scheme do not match this Power
(c) Unity's own in-Editor MCP server	shipped inside com.unity.ai.assistant; UI at Edit > Project Settings > AI > Unity MCP	the MCP client connects straight to the in-Editor server	Deprecated — see below

On the deprecation of (c), and why it does not affect this Power. Unity's documentation states that the MCP server inside the in-Editor AI assistant package is deprecated and that the Unity CLI (unity mcp) takes its place, shipping its own MCP server that speaks the same protocol (Unity CLI as the replacement for the in-Editor MCP server, retrieved 2026-10-21; the same notice appears in the package docs, com.unity.ai.assistant — Get started with MCP server, retrieved 2026-10-21). The same Unity page states that third-party MCP packages installed from GitHub to give agents access to Unity are unaffected by that deprecation. Project (a) — the bridge this Power uses — is therefore explicitly outside the scope of the deprecation, and this Power is not obsolete because of it.

Prerequisites

• Unity Editor installed with a project open (see Setup alternatives below if you have restricted installation access) — Unity 6.4 is the target, Unity 6.0 the minimum for this Power
• Kiro IDE installed
• MCP for Unity v10.3.0 or newer (minimum v10.0.0) — if the project has com.coplaydev.unity-mcp 9.6.8 or older installed, upgrade it; the 9.6.8 → 10.3.0 change is purely additive, so there is no migration cost. Read Upgrading the bridge before you start: the C# package and the Python server are pinned separately, and upgrading only one breaks the bridge
• Python 3.10 or newer plus uv — the bridge's server is a Python package (mcpforunityserver on PyPI) launched through uv/uvx. The MCP for Unity setup wizard can install uv for you; on Windows, point "Choose UV Install Location" at the WinGet shim (%LOCALAPPDATA%\Microsoft\WinGet\Links\uv.exe) if several uv.exe copies are on PATH
• Node.js 18+ (for development/typechecking only — not required for basic usage with the Power)

Setup alternatives: Choose the installation method that works for your environment:

• Standard setup: Follow the steps below (requires unrestricted software installation access)
• Restricted environment: See the Troubleshooting section for alternative configuration options (e.g., stdio transport mode — a method that runs the MCP server as a child process instead of using HTTP)
• Enterprise/managed environment: If your organization manages software installations, consult your IT department about licensing and installation procedures

Unity Editor offers a free Personal license for individuals, students, hobbyists, and small teams.

Installation

Step 1 — Install this Power in your IDE

Open Kiro → Left panel click Powers icon → Click "+" button → Select "Add Custom Power" → Select this project's root directory

Note: The underlying Unity MCP tools (CoplayDev/unity-mcp) are open-source and can also be used independently with any MCP-compatible client.

Step 2 — Install unity-mcp and Start MCP Server in Unity

1. Open Unity Editor → Window → Package Manager

   

2. Click "+" → "Add package from git URL..." → Paste the following URL and click Add. Note the pinned #v10.3.0 tag — do not replace it with #main:

   https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#v10.3.0
   

   

   Corrected instruction. Earlier versions of this README told you to use ...?path=/MCPForUnity#main. That was wrong, and the failure it causes was reproduced on a real install (verified 2026-10-21). Unity resolves a git UPM dependency once and then caches the resolved commit — a moving ref like #main does not track the branch. The verification machine's Packages/manifest.json said #main while the installed package was still 9.6.8 and upstream was already 10.3.0: stranded for months with no update prompt anywhere in Package Manager. A months-old bridge no longer matches the tool surface this Power documents, which is a direct cause of "the AI can't drive Unity".

   Alternatives to the pinned git URL:

   • OpenUPM: openupm add com.coplaydev.unity-mcp — a registry install, so Package Manager offers an update when a newer version ships
   • Asset Store: the "MCP for Unity" listing, then Package Manager → My Assets

   To upgrade later, change the tag — that is what forces Unity to re-resolve. Either edit Packages/manifest.json:

   "com.coplaydev.unity-mcp": "https://github.com/CoplayDev/unity-mcp.git?path=/MCPForUnity#v10.3.0"

   …or remove the package and re-add the git URL with the new tag. Then follow Upgrading the bridge — the UPM package is only half of the upgrade.

3. On first import the package opens a setup wizard. The persistent UI afterwards is Window → MCP for Unity, which starts/stops the server, switches transport, and reconfigures clients.

   

   The screenshot above was taken on an older build whose menu item read "Toggle MCP Window". Current builds use Window → MCP for Unity.

4. Confirm the status panel reads Connected, and read the server endpoint/port it displays — you will need that port below. Restart Server is the recovery action.

   

Pick exactly one MCP registration path

Two different mechanisms can register the Unity MCP server with Kiro, and they write to the same config file under different names. Running both leaves two servers pointing at the same Unity Editor, which produces duplicate tool surfaces and ambiguous resource reads.

• Path A — let this Power register the server. Install the Power and leave its mcp.json alone. A Legacy (POWER.md) power's MCP servers are registered into ~/.kiro/settings/mcp.json under the Powers section, with the server name namespaced by Kiro.
• Path B — let Unity configure Kiro. In Unity, Window → MCP for Unity → Configure All Detected Clients (or select Kiro and Configure Selected). The package writes a server entry named unityMCP into the same file.

If Kiro's MCP panel shows two Unity MCP servers, disable one and restart Kiro. The three config locations that matter: this Power's own mcp.json, user-level ~/.kiro/settings/mcp.json, and workspace-level .kiro/settings/mcp.json.

MCP Connection Configuration

Automatic Configuration (Recommended)

In Unity, Window → MCP for Unity → confirm the transport is HTTP → Configure All Detected Clients (or select Kiro and Configure Selected). Kiro is a first-class supported client, so this writes a port-accurate entry into ~/.kiro/settings/mcp.json under the server key unityMCP.

Read the real port

Do not treat 8080 as a constant. The port is whatever the server was launched with (--http-url), it is user-editable, and 8080 collides with other services (upstream names Tailscale as an example and suggests moving to 8090). The MCP for Unity window shows the live endpoint — if it is not 8080, the URL is http://127.0.0.1:<that port>/mcp.

You can also read the port straight off disk: the running server writes a pidfile named after its port under the Unity project.

<UnityProject>\Library\MCPForUnity\RunState\mcp_http_<port>.pid

So mcp_http_8080.pid means the server is serving http://127.0.0.1:8080. On the install this Power was verified against, that is exactly what was there — the server's own command line was mcp-for-unity --transport http --http-url http://127.0.0.1:8080 --project-scoped-tools --pidfile ...mcp_http_8080.pid.

Manual Configuration (last resort)

Edit mcp.json only if the two steps above did not produce a working entry.

HTTP mode (default transport — local-only, communicates with the Unity Editor on your machine):

Security Note: HTTP is used intentionally here. The server binds loopback only (127.0.0.1 / ::1); binding a LAN address requires Advanced Settings → Allow LAN Bind (HTTP Local), and a remote endpoint must be https://. Traffic on the default setup never leaves your machine, so HTTPS is not required.

{
  "mcpServers": {
    "unity-mcp": {
      "url": "http://127.0.0.1:8080/mcp",
      "type": "http",
      "env": {},
      "disabled": false
    }
  }
}

Replace 8080 with the port shown in the Unity window. The mode key is type, not transport. 127.0.0.1 is deliberate: upstream docs print localhost, but the Unity side's own default is the literal 127.0.0.1, and on Windows localhost can resolve to ::1 first.

Connection methods: HTTP (simpler, recommended) and stdio (backup option). Choose HTTP unless you hit a port conflict or a firewall.

Stdio mode (fallback — runs the MCP server as a subprocess, a separate process managed by Kiro). The PyPI distribution is mcpforunityserver and the console entrypoint is mcp-for-unity; --transport stdio is required. There is no unity-mcp package on PyPI — earlier versions of this README documented uvx unity-mcp, which is why that fallback never launched.

Windows (use an absolute uvx.exe path — the WinGet shim is the recommended one):

{
  "mcpServers": {
    "unity-mcp": {
      "command": "C:/Users/<you>/AppData/Local/Microsoft/WinGet/Links/uvx.exe",
      "args": ["--from", "mcpforunityserver", "mcp-for-unity", "--transport", "stdio"],
      "type": "stdio",
      "env": {},
      "disabled": false
    }
  }
}

macOS/Linux (uvx on PATH is usually fine):

{
  "mcpServers": {
    "unity-mcp": {
      "command": "uvx",
      "args": ["--from", "mcpforunityserver", "mcp-for-unity", "--transport", "stdio"],
      "type": "stdio",
      "env": {},
      "disabled": false
    }
  }
}

Upgrading the bridge: two version pins you must keep in sync

MCP for Unity is two components, each with its own separately pinned version. This is the most confusing part of upgrading it, and all of the following was observed on a live 9.6.8 → 10.3.0 upgrade on 2026-10-21.

Component	What it is	Where its version is pinned
UPM package (C# editor side)	com.coplaydev.unity-mcp in your Unity project	Packages/manifest.json — the git tag, or the registry version
Python MCP server	PyPI distribution mcpforunityserver, entrypoint mcp-for-unity	the --from "mcpforunityserver==<version>" argument of the command line Unity launches

The pre-upgrade launch line, observed verbatim:

uvx --from "mcpforunityserver==9.6.8" mcp-for-unity --transport http --http-url http://127.0.0.1:8080
  --project-scoped-tools --pidfile <UnityProject>\Library\MCPForUnity\RunState\mcp_http_8080.pid
  --unity-instance-token <token>

Upgrading the UPM package does not upgrade the Python server. After the manifest moved to #v10.3.0 and Unity imported and compiled the v10.3.0 C# cleanly, the running server still reported version 9.6.8 — it was executing an older cached copy.

The mismatch breaks the bridge selectively, which makes it very confusing. With C# at 10.3.0 and Python at 9.6.8, every Unity-dependent tool call returned {"success":false,"error":"Unity session not available; please retry","data":{"reason":"no_unity_session",...}}, while server-only tools such as debug_request_context kept answering normally. The server looks alive; nothing that touches Unity works.

Upgrade procedure

1. Change the UPM pin — edit the tag in Packages/manifest.json, or remove and re-add the git URL with the new tag. A moving ref like #main will not re-resolve.
2. Optional but recommended on a slow network: pre-seed the uv cache with uvx --from "mcpforunityserver==10.3.0" mcp-for-unity --help. On the verified upgrade this is why Unity could then start the server with --offline.
3. Let Unity import and compile the package; confirm the editor log shows no error CS.
4. Stop the stale server process chain (uvx → uv → mcp-for-unity → python). It will not pick up the new version by itself.
5. Delete the stale pidfile if one is left behind at <UnityProject>\Library\MCPForUnity\RunState\mcp_http_<port>.pid. On the verified upgrade it was left there after the kill and had to be removed by hand.
6. Start the server from Unity: Window → MCP for Unity → Start Server. This explicit step was required — the server restarted neither after the package upgrade nor after the process chain was killed. Unity then relaunched it with a matching pin (uvx --offline --from "mcpforunityserver==10.3.0" ...), from a new cache archive, with the port listening and both components at 10.3.0.
7. Reconnect Kiro's MCP server (MCP Server panel → reconnect, or restart Kiro). An upgrade always invalidates the client's MCP session — see the next paragraph.
8. Check both pins agree: debug_request_context reports the server version, manage_packages(action: "list_packages") reports the package version.

Two errors that look alike and are not

After the restart, the already-connected client's calls failed with {"jsonrpc":"2.0","id":"server-error","error":{"code":-32600,"message":"Session not found"}}. That is the MCP transport session, not the Unity bridge:

Error	Layer	Fix
Session not found (-32600)	the MCP transport session between Kiro and the Python server	reconnect Kiro's MCP server, or restart Kiro. Version pins are irrelevant
no_unity_session / "Unity session not available"	the Unity bridge between the Python server and the Editor	match the two version pins first; if they already match, check that the Editor is open and not compiling. Reconnecting does nothing

What v10.3.0 is

v10.3.0 is the current non-prerelease release (GitHub tag v10.3.0, published 2026-10-04, asset unity-mcp-10.3.0.mcpb), and the matching mcpforunityserver-10.3.0 is on PyPI (uploaded the same minute, Python >= 3.10). Release-notes items relevant here: a Unity 6000.6 InstanceIDToObjectCompat fix, stdio port-discovery refreshed before reconnect backoff, a read_console fix so the Console window's filters no longer hide entries, upstream docs on where to look when a tool is missing from the tool list, the new Blender Bridge, and auto-discovery of fal / OpenRouter asset-generation models.

Its server CLI (mcp-for-unity --help on 10.3.0) accepts --default-instance, --transport {stdio,http}, --http-url, --http-host, --http-port, --http-remote-hosted, the --api-key-* group (for remote-hosted auth), --unity-instance-token, --pidfile and --project-scoped-tools. This confirms the stdio fallback form above is correct; the only refinement is that pinning a version in --from is what Unity's own launcher does.

What changed on the tool surface, measured

After the upgrade the client reconnected and the v10 tools were called directly. The live tool list went from 43 on 9.6.8 to 49 on 10.3.0 on the same machine. The six additions are blender_bridge, generate_audio, generate_image, generate_model, import_model and import_model_file; nothing was removed or renamed, so the upgrade costs this Power no migration work. Treat 49 as the real number — upstream's README says "48 focused MCP tool entrypoints", and the live count wins.

All six additions live in a new tenth tool group, asset_gen, which manage_tools(action: "list_groups") reports with enabled: false and default_enabled: false. That off-by-default state was confirmed live, and it is the safe default: these tools generate 3D models, images and audio through paid third-party services on your own API key. Activating the group exposes tools that spend credits, so nothing in this Power routes to it, and none of the six was ever called during verification. The other nine groups came back unchanged from 9.6.8.

One security improvement worth knowing: on 10.3.0 debug_request_context masks the --unity-instance-token value as ***, where 9.6.8 printed it in clear text. Checking debug output before sharing it is still a good habit, just far less critical on v10. Its session_state block also no longer returns the derived_key / all_keys_in_store fields that 9.6.8 did.

What the write path proved, and the one finding that changes how you chain calls

A final round of verification stopped reading and started writing. Everything went into an isolated Assets/_MCPVerify/ folder with MCPVerify_* object names and was deleted afterwards; the project was then confirmed back at baseline — SampleScene with its original 3 roots and their original component sets, and a full manage_asset(action: "search", search_pattern: "*") returning its original 20 assets, all stock Unity template content.

Verified on 10.3.0: manage_asset folder create/delete; create_script, get_sha, validate_script, find_in_file's success path, script_apply_edits and delete_script; manage_gameobject create/modify/duplicate/delete; manage_components add and set_property; manage_prefabs(create_from_gameobject); refresh_unity; and run_tests → get_test_job as a complete async job lifecycle (running → succeeded in about 7.5 s). A later round built a throwaway EditMode test assembly — one deliberately passing test, one deliberately failing — ran it and deleted it, so EditMode pass/fail reporting and the assembly_names filter are verified too (summary: {total: 2, passed: 1, failed: 1, skipped: 0, durationSeconds: 0.33, resultState: "Failed(Child)"}). Two things worth knowing before you write a polling loop: a job's status is the test outcome, so failed means an assertion failed rather than the run breaking, and succeeded with total: 0 means nothing ran; and failure detail arrives in progress.failures_so_far while result.results was null in every observed run. PlayMode is verified too, in a later round. A throwaway PlayMode assembly — the EditMode recipe with includePlatforms: [] instead of ["Editor"], which is the single field that makes an assembly PlayMode-capable — ran three tests: two passed, one of them a [UnityTest] coroutine checking that Time.frameCount really advanced across frames, and one failed on purpose (summary: {total: 3, passed: 2, failed: 1, skipped: 0, durationSeconds: 0.0716135, resultState: "Failed(Child)"}). The response shape was identical to EditMode's, so there is nothing mode-specific to re-learn, and the MCP session survived the run's full domain reload — though instance IDs still do not survive it. About 5.2 s wall clock against EditMode's 4.2 s, with init_timeout: 120000 passed as upstream recommends; whether a smaller value would do is unverified, so keep passing it.

Instance IDs are volatile, and this is the finding that matters most for multi-step work. A newly created GameObject came back with a negative id (-5560); once Unity registered the object that id no longer resolved (not found using method 'by_id') and the object answered to a positive one instead (50436, later 50470). Worse, a refresh_unity recompile renumbered objects nobody had touched — Main Camera 49224 → 50412, Directional Light 49234 → 50422, Global Volume 49242 → 50430. So: carry an object's name or path between steps, re-resolve an id immediately before the call that uses it, and never hold one across a recompile or domain reload.

Three smaller corrections from the same pass: the three object tools disagree about target (manage_components accepts an int id, manage_gameobject needs a string and reads it as a name by default, manage_prefabs requires the name) — passing the name satisfies all three; script_apply_edits takes name + path, not uri; and refresh_unity's mode and compile are string enums (if_dirty/force and none/request), so compile: true is rejected. Also confirmed: manage_gameobject(duplicate) ignores name and produces Unity's <original>_Copy, and Unity 6.4's current linearDamping (replacing the obsolete drag) is settable through manage_components.

Install Auto-Guidance Hook (Recommended)

This Power ships a UserPromptSubmit hook (Kiro 1.0 v1 schema) that reminds the AI to activate the Power and load the appropriate Steering File before processing each request.

mkdir -p .kiro/hooks
cp hooks/unity-power-auto-activate.json .kiro/hooks/unity-power-auto-activate.json

Verify Connection

Type any Unity-related command in the IDE (e.g., "List all objects in the current scene"). If the AI responds correctly, the connection is successful.

Usage

Tell the AI what you'd like to do in natural language. It will automatically select and execute the appropriate MCP tools.

Example Commands

"Set all models in the Characters folder to Humanoid rig"
"Create a 3D first-person scene"
"Build for Windows"
"Check the project's code architecture"
"Check Android platform compatibility"
"Analyze dependencies for hero.fbx"

Demo: Build an Interactive Scene and Run a Full Quality Check

The following demonstration uses an interactive 3D scene with collectible items as an example. We chose this scenario because it demonstrates multiple Unity systems (physics, rendering, UI, scripting) in a compact example. The same workflow steps (scene setup, code quality checks, performance analysis, platform compatibility) apply to any Unity project — whether building games, simulations, training applications, architectural visualizations, or other interactive experiences.

Non-game alternative: For an architectural visualization project, replace the 3D scene with a building walkthrough, replace collectible objects with interactive waypoints, replace scoring with progress tracking, and replace the HUD with an information panel. The workflow steps remain identical.

Phase 1: Create the Scene (Game Example)

Alternative for non-game projects: Replace collectible objects with interactive waypoints, scoring with progress tracking, and the HUD with an information panel. The workflow steps remain identical.

First, build a playable 3D scene:

Create a 3D scene with:
- Terrain (rolling grassland)
- Directional and ambient lighting
- Character controller (WASD movement + mouse look)
- Collectible objects (gems and coins scattered around)
- HUD Canvas with score and timer display
Name the scene Level01 and save it

Next, add interactive gameplay mechanics:

Add core interaction gameplay:
1. Collection system: walk near objects to collect, objects glow when in range
2. 5 collectible items (colored gems) placed around the terrain
3. Items disappear with particle effects when collected
4. Scoring system: top-left score display, +100 per item collected
5. Show "COMPLETE" when all items are collected

Now create a level configuration system:

Create a ScriptableObject called LevelConfig with: level name (string), difficulty (int, 1-10),
time limit (float), enemy wave list (nested: enemy type string + count int + spawn delay float),
and generate a custom Inspector

Why these checks matter: In production Unity projects, catching architecture violations and performance issues early prevents costly refactoring later. The checks below typically surface 80% of common issues in under a minute.

Phase 2: Quality Checks and Optimization

With the scene in place, run a code quality check:

Check all C# code against MVC architecture rules, scan naming conventions,
layer dependencies and circular references, list all violations with fix suggestions

Then scan for performance issues:

Scan all C# scripts for performance anti-patterns, analyze current scene Draw Calls
and memory usage, generate a complete performance report sorted by severity

Verify cross-platform compatibility:

Check all Shader platform compatibility for Android and iOS, verify memory budgets,
categorize issues as Error/Warning/Suggestion, provide alternatives for incompatible Shaders

Finally, build and check results:

Build the project with Android release configuration, parse build logs for errors,
list each error's type, file location, and fix suggestions

Development

The TypeScript modules in src/ are standalone — there is no bundler and no build step. The test suite and the TypeScript compiler config are developer-local (git-ignored), so a fresh clone has no test runner configured; typecheck with explicit compiler flags instead:

npm install   # devDependencies only — the Power itself has no runtime dependencies

# typecheck (bash)
npx tsc --noEmit --strict --target ES2022 --module ESNext --moduleResolution bundler --skipLibCheck src/*.ts

# typecheck (PowerShell)
npx tsc --noEmit --strict --target ES2022 --module ESNext --moduleResolution bundler --skipLibCheck (Get-ChildItem src -Filter *.ts | ForEach-Object FullName)

Project Structure

kiro-unity-accelerator/
├── POWER.md                    # Main document for the AI assistant
├── mcp.json                    # MCP Server connection config
├── steering/                   # Domain knowledge Steering Files (15)
├── templates/                  # Built-in templates
│   ├── presets/                # Asset Presets (5)
│   ├── scaffolds/              # Scene Scaffolds (5)
│   ├── build-configs/          # Build Configurations (4)
│   ├── platform-profiles/      # Platform Profiles (5, including XR/VR)
│   ├── architecture-rules/     # Architecture Rules (3)
│   └── workflows/              # Workflow Templates (3)
├── src/                        # TypeScript tool modules (40+)
├── hooks/                      # Hook template (copy into .kiro/hooks/)
├── workshop/                   # Step-by-step prompt tutorials
├── image/                      # Documentation images
└── package.json

Troubleshooting

Problem	Solution
Kiro cannot connect to Unity	Ensure Unity Editor is open with a project loaded → Window → MCP for Unity → confirm the status panel reads Connected (use Restart Server if not)
Unity session not available; please retry / "reason":"no_unity_session" on every Unity call, while debug_request_context still answers	First suspect: the C# package and the Python server are on different versions. Verified 2026-10-21 — C# at 10.3.0 with Python still at 9.6.8 produced exactly this, and it is selective, so the server looks healthy. Compare debug_request_context's server version with the package version from manage_packages(action: "list_packages"); if they differ, follow Upgrade procedure. If they already match, check that the Editor is open and not compiling. This is not the same as Session not found — reconnecting Kiro will not fix it
Session not found (JSON-RPC -32600)	The MCP transport session is gone, almost always because the server restarted. Reconnect in Kiro's MCP Server panel, or restart Kiro, to get a new session and re-read the tool list. Every bridge upgrade causes this. Distinct from no_unity_session, which is the Unity bridge layer
Stuck on an old bridge version with no update offered	Check Packages/manifest.json: if the entry ends in #main, Unity resolved it once and cached it, so it never tracks the branch. Replace it with an explicit tag (#v10.3.0) to force a re-resolve, then follow Upgrade procedure
Port 8080 is occupied	Change the port in MCP for Unity settings (upstream suggests 8090), re-run Configure All Detected Clients, restart Kiro, and make the url in mcp.json match the port shown in the Unity window
A documented tool is reported as not existing	Possibly its tool group is inactive — the bridge's declared default is core only, though on the verified install every tool was callable with no activation. Run manage_tools(action: "list_groups"), then manage_tools(action: "sync"), then manage_tools(action: "activate", group: "<name>"), and refresh or reconnect the MCP server afterwards (Kiro may cache the tool list). list_groups can report enabled: false for a group whose tools work, so judge by whether the retry succeeds
Tool call denied by user's permissions	A Kiro permission rule blocked the call before Unity saw it — not a bridge fault. Kiro exposes this Power's server as power-kiro-unity-accelerator-unity-mcp; check ~/.kiro/settings/permissions.yaml (and the workspace-level file) for capability: mcp entries with effect: deny matching power-<powerName>-<serverName>/<tool>, and relax the rule if you want that tool available. On the machine this Power was verified against, such a rule denied manage_build and made the whole build workflow unrunnable
Unknown action inside a batch_execute	batch_execute goes straight to Unity and bypasses the bridge's Python server layer, so a server-layer action fails there even though it works. Re-run that one call directly before concluding the action does not exist
Two Unity MCP servers registered	Open ~/.kiro/settings/mcp.json and Kiro's MCP panel; if both the Power's entry and unityMCP are present, disable one and restart Kiro (see "Pick exactly one MCP registration path")
Unity 6.3+ with the Unity AI Assistant package installed	The AI Assistant bundles a newer System.Collections.Immutable than the Roslyn dependency used by validate_script / execute_code expects. Upstream's fix is to place System.Collections.Immutable v9.0.0 into Assets/Plugins/
Asset operations unresponsive	Unity may be compiling; wait for compilation to complete, or read the mcpforunity://editor/state resource
TypeScript type errors	Run the flag-based typecheck in the Development section above; ensure npm install has been run

Security

See CONTRIBUTING for more information.

License

This library is licensed under the MIT-0 License. See the LICENSE file.