diff --git a/README.md b/README.md
index 41dac75..7f0ee00 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,7 @@ Now just run `oc` to start OpenCode with Claude Max.
 |---------------------|---------|-------------|
 | `CLAUDE_PROXY_PORT` | 3456 | Proxy server port |
 | `CLAUDE_PROXY_HOST` | 127.0.0.1 | Proxy server host |
+| `CLAUDE_PROXY_WORKDIR` | (process cwd) | Base working directory used by MCP file/shell tools |
 
 ## How It Works
 
diff --git a/src/mcpTools.ts b/src/mcpTools.ts
index ed8b778..84b28f2 100644
--- a/src/mcpTools.ts
+++ b/src/mcpTools.ts
@@ -8,7 +8,7 @@ import { glob as globLib } from "glob"
 
 const execAsync = promisify(exec)
 
-const getCwd = () => process.cwd()
+const getCwd = () => process.env.CLAUDE_PROXY_WORKDIR || process.cwd()
 
 export const opencodeMcpServer = createSdkMcpServer({
   name: "opencode",