Content
<div align="center">
# Recaf MCP
> *「"Turn Recaf into an API that LLMs can call"」*
[](https://adoptium.net/)
[](https://www.python.org/)
[](https://www.coley.software/recaf4/)
[](https://modelcontextprotocol.io/)
[](https://qm.qq.com/q/KWcs2UBtYK)
<br>
[中文版](README_CN.md)
<br>
**Recaf 4 MCP bridge — operate a Recaf workspace via MCP protocol for JVM bytecode analysis and editing.**
<br>
A Java plugin runs inside Recaf exposing a local HTTP API; a Python MCP server turns that API into MCP tools consumable by LLM clients.
<br>
[Tools](#tools) · [Quick Start](#quick-start) · [Bytecode Editing](#bytecode-editing) · [Install](#install-plugin)
</div>
---
## Tools
### Workspace
`get_workspace_info` `open_workspace` `close_workspace` `add_supporting_resource` `list_supporting_resources` `fetch_current_class` `get_selected_text`
### Classes
`get_all_classes` `get_class_info` `get_class_source` `get_bytecode_of_class` `get_methods_of_class` `get_fields_of_class` `get_inner_classes` `get_annotations_of_class` `get_raw_class_bytes`
### Methods
`get_method_by_name` `get_method_bytecode` `get_method_info`
### Search
`search_classes_by_name` `search_members_by_name` `search_strings` `search_numbers` `search_instructions`
### Cross References
`get_xrefs_to_class` `get_xrefs_to_method` `get_xrefs_to_field` `get_callers_of_method` `get_callees_of_method` `get_overrides_of_method`
### Refactor
`rename_class` `rename_method` `rename_field` `rename_package` `rename_local_variable` `apply_mappings`
### Decompilers
`list_decompilers` `set_active_decompiler` `decompile_class_with`
### Inheritance
`get_superclasses` `get_interfaces` `get_direct_subclasses` `get_all_subclasses` `get_implementors`
### Resources & Export
`get_all_file_names` `get_file_content` `get_manifest` `get_strings_from_resources` `export_workspace` `get_modified_classes` `revert_class`
---
## Bytecode Editing
Full bytecode read/write: instruction-level editing, JASM text assembly, access flag editing, method/field CRUD, try-catch blocks, class byte replacement, workspace export.
### Instructions
`list_method_instructions` `get_method_bytecode` `replace_instruction` `insert_instruction` `remove_instruction`
### Method Body
`assemble_method` `replace_method_body`
### Access Flags
`edit_class_access` `edit_method_access` `edit_field_access`
### Method / Field CRUD
`add_method` `remove_method` `add_field` `remove_field`
### Other
`set_try_catch_blocks` `replace_class_bytes` `save_workspace`
---
## Requirements
- Java 25
- Python 3.10+
- `recaf.jar`
## Quick Start
### 1. Provide recaf.jar
The build looks for Recaf in this order:
1. `RECAF_JAR` env var
2. `libs/recaf.jar`
3. `../recaf/recaf.jar`
```powershell
$env:RECAF_JAR="D:\deobf\recaf\recaf.jar"
```
### 2. Build the Plugin
```powershell
.\gradlew.bat jar
```
Output: `build/libs/recaf-mcp-plugin-0.1.0.jar`
### 3. Install Plugin
Copy the jar to Recaf's plugin cache directory `%APPDATA%/Recaf/plugins/` and launch Recaf.
On successful load:
```
Recaf MCP plugin listening on http://127.0.0.1:8750
```
### 4. Install Python Dependencies
```powershell
pip install -r requirements.txt
```
### 5. Start the MCP Server
```powershell
python recaf_mcp_server.py --http --port 8751
```
Or use the launcher script:
```powershell
.\start_recaf_mcp_http.ps1
```
---
## MCP Config
```json
{
"mcpServers": {
"recaf-mcp": {
"url": "http://127.0.0.1:8751/mcp"
}
}
}
```
## Ports
| Component | Address |
|---|---|
| Plugin HTTP | `127.0.0.1:8750` |
| MCP HTTP | `127.0.0.1:8751/mcp` |
Health check:
```powershell
Invoke-WebRequest http://127.0.0.1:8750/health
```
---
## Repository Structure
```text
.
├── src/ # Java plugin source
├── mcp-server/ # Python MCP server
├── libs/ # recaf.jar goes here
├── recaf_mcp_server.py # MCP server entry point
├── requirements.txt # Python dependencies
├── .mcp.json # Project MCP config
└── README.md
```
---
## Security
Binding to all interfaces exposes the MCP server with no authentication:
```powershell
python recaf_mcp_server.py --http --host 0.0.0.0
```
Use localhost by default, or place it behind a firewall / VPN.
---
<p align="center">
<em>LLM Client -> MCP Server -> Recaf Plugin -> Recaf Workspace</em>
</p>
