unity-api-mcp

MCP server that gives AI agents accurate Unity API documentation. Prevents hallucinated signatures, wrong namespaces, and deprecated API usage.

Supports Unity 6 (one database per minor stream), Unity 2023, and Unity 2022 LTS. Works with Claude Code, Cursor, Windsurf, or any MCP-compatible AI tool. No Unity installation required. See the supported versions. New Unity releases are detected and built automatically every week.

Quick Start

Add to your MCP config (.mcp.json, mcp.json, or your tool's MCP settings), setting UNITY_VERSION to match your project:

{
  "mcpServers": {
    "unity-api": {
      "command": "uvx",
      "args": ["unity-api-mcp"],
      "env": {
        "UNITY_VERSION": "6000.3"
      }
    }
  }
}

Valid values: a Unity 6 stream like "6000.3", or "6", "2023", "2022".

On first run the server downloads the correct database (~20-30 MB) to ~/.unity-api-mcp/.

How It Works

1. Version detection. The server figures out which Unity version to serve:

Priority	Source	Example
1	UNITY_VERSION env var	"2022", "6", "6000.3", or "6000.3.8f1"
2	UNITY_PROJECT_PATH	Reads ProjectSettings/ProjectVersion.txt, maps 2022.3.62f1 to "2022", 6000.3.8f1 to "6000.3"
3	Default	"6"

2. Database download. If the database for that version isn't cached locally, it downloads from GitHub. Unity 6 minor streams (6000.0, 6000.3, 6000.5, …) get their own per-stream database, falling back to the generic 6 database when a stream database isn't published. Cached databases are freshness-checked against the release on startup, so weekly rebuilds reach existing installs automatically.

3. Serve. All tool calls query the version-specific SQLite database. Every query returns in <15ms.

Each version has its own database with the correct signatures, deprecation warnings, and member lists for that release.

Tools

Tool	Purpose	Example
search_unity_api	Find APIs by keyword	"Tilemap SetTile", "async load scene"
get_method_signature	Exact signatures with all overloads	UnityEngine.Physics.Raycast
get_namespace	Resolve using directives	"SceneManager" -> using UnityEngine.SceneManagement;
get_class_reference	Full class reference card	"InputAction" -> all methods/fields/properties
get_deprecation_warnings	Check if an API is obsolete	"WWW" -> Use UnityWebRequest instead

Coverage

All UnityEngine and UnityEditor modules, plus packages parsed from C# source: Input System, Addressables, uGUI (incl. TextMeshPro on Unity 6), AI Navigation, and Netcode. ~42,500 records per Unity 6 database, ~500 deprecation warnings each.

Full version list: db-v1 release page. CI regenerates that table on every build. New Unity patches are detected and built automatically every Monday.

Does not cover third-party assets (DOTween, VContainer, Newtonsoft.Json). For those, rely on project source.

Benchmarks

Measured, not promised: 25 research questions across 3 testbeds, answered by 3 agent configs, every answer judged against ground truth verified in the source beforehand. The full harness lives in docs/benchmark/ and re-runs with one command.