使用说明

ue-codegraph-mcp

MCP server for indexing and querying Unreal Engine C++ codebases.

Indexes your UE project's Source/ directory into a local SQLite database and exposes 17 MCP tools so Claude Code can answer questions about call graphs, class structure, #include dependencies, and Blueprint-exposed symbols — without reading raw files every time.

Features

Call graph analysis — find all callers of a function, trace call chains from A → B
Class analysis — methods, fields, base classes, UE macros (UCLASS, UPROPERTY, UFUNCTION)
Blueprint exposure — list all BlueprintCallable functions and BlueprintReadWrite properties
#include dependency graph — what a file includes, and what includes it (transitive support)
Symbol search — FTS5 full-text search across 40k+ symbols with prefix matching
Incremental indexing — re-indexes only changed files (hash + mtime based)
Standalone CLI — use ue-graph commands directly from the terminal without Claude

Prerequisites

Requirement	Version	Check
Node.js	22 LTS	`node --version`
npm	9+	`npm --version`
Claude Code	latest	`claude --version`

Use an even-numbered Node.js release (20, 22 LTS or 24). Odd-numbered "Current" releases (v23, v25, etc.) are incompatible with tree-sitter's native bindings and will fail to parse files. Node 24 needs better-sqlite3 12+ (this repo ships 13); the older 11.x crashes the process under garbage collection on Node 24.

Installation

1. Install Node.js 22 LTS

Download from https://nodejs.org (click the LTS tab) or use winget:

winget install OpenJS.NodeJS.LTS

2. Run `setup.bat`

cd C:\path\to\ue-codegraph-mcp
.\setup.bat

setup.bat will:

Verify Node.js 22 LTS
Install node-gyp globally (needed for native module builds)
Run npm install (builds tree-sitter and better-sqlite3 from source)
Run npm link to register the ue-graph CLI globally
Optionally index your project and generate mcp.json

If the native build fails, install Visual Studio Build Tools with the C++ build tools workload, then re-run setup.bat.

3. Index your project

ue-graph index "G:\YourProject\Source" my-project

Output:

Indexing G:\YourProject\Source as "my-project" (project)...

Done!
  Files:   1784  (new: 1784, changed: 0)
  Symbols: 45623
  Macros:  3210
  Calls:   28450
  Includes: 9120
  Time: 32.5s

4. Register with Claude Code

claude mcp add -s user ue-codegraph node "C:\path\to\ue-codegraph-mcp\build\index.js"

Verify with claude mcp list. Then start Claude Code in your project directory and run /mcp to confirm the server is connected.

Usage in Claude Code

Once registered, Claude automatically uses the MCP tools when you ask natural-language questions:

"Find everything that calls SetHP"
"Trace the call chain from DamageMyPlayer to ApplyDamage"
"Analyze the UAMirLuaManager class"
"Which files include AMirCharacter.h?"
"Show all BlueprintCallable functions in UAMirAbilityComponent"

CLI Commands

Use ue-graph directly from the terminal without Claude Code.

Index management

ue-graph index <path> [name]     # Index a codebase
ue-graph status                  # Show indexed codebases and stats
ue-graph reindex <file...>       # Re-index specific files (deleted files are removed)
ue-graph watch [path]            # Watch for edits and re-index changed files automatically
ue-graph ui [--port N]           # Open the visual explorer in your browser
ue-graph delete <id|name|all>    # Remove a codebase from the index

Call graph

ue-graph callers SetHP                       # Who calls SetHP?
ue-graph callees BeginPlay                   # What does BeginPlay call?
ue-graph chain DamageMyPlayer SetHP          # Call path from A to B

Class analysis

ue-graph analyze UAMirLuaManager             # Methods, fields, UE macros
ue-graph hierarchy AAMirCharacter            # Inheritance tree (up + down)
ue-graph blueprint UAMirLuaManager           # Full Blueprint interface

Search

ue-graph search "SetHP"                      # FTS symbol search
ue-graph code "CL2LG_MY_CHARACTER_SPAWN_REQ" # Code text pattern search
ue-graph refs DamageMyPlayer                 # Where is this symbol used?

UE Macros

ue-graph macros UFUNCTION                    # All UFUNCTION macros
ue-graph macros UFUNCTION BlueprintCallable  # Filter by specifier
ue-graph deps "G:\...\MyActor.h"            # #include dependency graph

Incremental indexing

Edits are applied in proportion to what changed, not to the size of the codebase.

Change detection compares size, mtime and content hash, so only touched files are parsed.
File watcher: while the MCP server runs (or ue-graph watch), saving a .h/.cpp re-indexes just that file (debounced). On start-up the server also catches up on edits made while it was off. Disable with UE_CODEGRAPH_WATCH=0.
Scoped linking: after a re-parse only the affected rows are re-linked: the file's own calls, references, base classes and includes, plus unresolved rows elsewhere that point at a symbol name that was re-created. Files keep their row id on re-index, so #include links from other files stay valid.
Include-aware resolution: when several symbols share a name (Tick, BeginPlay...), a call resolves to the one in the same file, then the paired header, then the include closure (3 hops), instead of an arbitrary match. If a file's #include list changes, the files that include it (2 hops) are re-ranked.
Parallel parsing: large batches are parsed on worker threads (UE_CODEGRAPH_WORKERS=N, 0 = single thread) while the main thread writes the previous batch to SQLite.
When more than 30% of files changed (or on the first index) a full link pass runs instead.

Parsing is file-local, so a header edit does not require re-parsing its includers. Their links are refreshed instead, which is what the scoped linking above does.

Rough numbers on a synthetic 3000-header project: full index 17 s single-threaded, 5.5 s with 6 workers; re-indexing one saved file takes about 50 ms.

Visual explorer

ue-graph ui            # http://localhost:4177

or ask Claude to call the open_viewer tool. Everything runs locally (bound to 127.0.0.1) and the page refreshes by itself when the index changes.

Tab	Shows
Overview	Counts, link quality, symbols by kind, UE macros, biggest classes, most-called functions, most-included headers
Class hierarchy	Ancestors and descendants of a class (engine/unindexed bases appear as dashed nodes)
Call graph	Callers and callees of a function, up to 4 levels
Includes	`#include` neighbourhood of a file in both directions
Modules	Folder-level dependency map (aggregated `#include` counts)

Click a node for details (members, UE macros, signature, includes), double-click to re-center, drag to rearrange, scroll to zoom. Purple dot = carries a UE macro (UCLASS...), green dot = Blueprint-exposed.

MCP Tools Reference

Tool	Description
`init_codebase`	Index a UE source directory
`get_index_status`	Show registered codebases and stats
`reindex_file`	Re-index specific files (normally automatic, see below)
`open_viewer`	Start the local web viewer and return its URL
`find_callers`	Find all callers of a function
`find_callees`	Find all functions called by a function
`find_call_chain`	Shortest call path from function A to B
`get_file_dependencies`	`#include` graph (includes + included-by)
`analyze_class`	Class methods, fields, UE macros, base classes
`get_class_hierarchy`	Ancestor and descendant class tree
`find_ue_macros`	Search UE macros by type and specifier
`get_macro_specifiers`	Get specifiers for a specific symbol's macro
`find_blueprint_exposed`	All `BlueprintCallable`/`BlueprintReadWrite` symbols
`get_blueprint_interface`	Full Blueprint interface of a class
`search_symbols`	FTS5 symbol search
`search_code`	Code text pattern search
`find_references`	Cross-reference lookup

Known Limitations

Issue	Workaround
`analyze_class` may fail on 3000+ line headers (forward declarations)	Use Grep + Read instead
Parent class lookup broken when `GENERATED_BODY()` is the only inheritance hint	Use `grep 'class Foo.*public'`
`find_callees` can mix results when multiple classes share the same method name	Calls are ranked by include closure, but without type information it can still pick the wrong overload
Databases indexed before the scoped-linking release attach `UCLASS`/`USTRUCT` to the class constructor	Delete the codebase and index it once more (`ue-graph delete <name>`)

Troubleshooting

All files fail with Invalid argument during indexing → Wrong Node.js version. Install Node.js 22 LTS, delete node_modules/, re-run setup.bat.

Native build errors (node-gyp, better-sqlite3) → Install Visual Studio Build Tools (C++ workload), then re-run setup.bat.

MCP server not visible in Claude Code → Confirm the path in claude mcp list is an absolute path. Restart Claude Code and run /mcp.

License

MIT