diff --git a/AGENT_HANDOFF.md b/AGENT_HANDOFF.md
index 69178bd..b14c10c 100644
--- a/AGENT_HANDOFF.md
+++ b/AGENT_HANDOFF.md
@@ -51,12 +51,15 @@ All five MCP tool handlers are complete:
 
 Total: 139 orchestration-only tests, all passing.
 
+## Completed (Phase 5)
+
+### Task 5.1 - MCP server skeleton ✅
+
+Minimal MCP stdio server in `src/server.js`. MCP initialize handshake succeeds. No tools registered yet.
+
 ## Next Pending
 
-### Phase 5 - MCP Server and Tool Registration
-
-- Register the five tools with the MCP server.
-- Implement the stdio server.
+### Task 5.2 - Register ask_chatgpt MCP tool
 
 ## General Rules
 
diff --git a/PROJECT_STATE.md b/PROJECT_STATE.md
index 21d045e..d9bff1c 100644
--- a/PROJECT_STATE.md
+++ b/PROJECT_STATE.md
@@ -7,7 +7,7 @@ ChatGPT MCP Server
 ## Status
 
 Planning complete.
-Phase 0 complete. Phase 1 complete. Phase 2 complete. Phase 3 complete. Task 4.1 complete. Task 4.2 complete. Task 4.3 complete. Task 4.4 complete. Task 4.5 complete. Phase 4 complete.
+Phase 0 complete. Phase 1 complete. Phase 2 complete. Phase 3 complete. Task 4.1 complete. Task 4.2 complete. Task 4.3 complete. Task 4.4 complete. Task 4.5 complete. Phase 4 complete. Task 5.1 complete.
 
 ## Current Phase
 
@@ -36,6 +36,7 @@ Phase 5 - MCP Server and Tool Registration
 - Task 4.3 — review_code MCP tool handler (`src/tools/review-code.js`, `test/tools/review-code.test.js`) ✅
 - Task 4.4 — debug_issue tool handler (`src/tools/debug-issue.js`, `test/tools/debug-issue.test.js`) ✅
 - Task 4.5 — architecture_review tool handler (`src/tools/architecture-review.js`, `test/tools/architecture-review.test.js`) ✅
+- Task 5.1 — MCP server skeleton (`src/server.js`) ✅
 
 ## Phase 3 Completion Summary
 
@@ -85,3 +86,7 @@ All five tool handlers are implemented and tested:
 - No MCP tool registration yet.
 - No server or router code yet.
 - That belongs to Phase 5.
+
+## Next Pending
+
+### Task 5.2 - Register ask_chatgpt MCP tool
diff --git a/TASKS.md b/TASKS.md
index 0c1ab57..a44ed03 100644
--- a/TASKS.md
+++ b/TASKS.md
@@ -406,3 +406,38 @@ All five tool handlers are implemented and tested:
 ---
 
 Phase 2 complete. Phase 3 complete. Phase 4 complete. Phase 5 next: MCP Server and Tool Registration.
+
+---
+
+## Phase 5 - MCP Server and Tool Registration
+
+### Task 5.1 - MCP server skeleton
+
+Create the minimal runnable MCP server in `src/server.js`.
+
+**Requirements:**
+- Use `McpServer` from `@modelcontextprotocol/sdk/server/mcp.js`.
+- Use `StdioServerTransport` from `@modelcontextprotocol/sdk/server/stdio.js`.
+- Create server with name `"chatgpt-mcp"` and version `"0.1.0"`.
+- Connect over stdio transport.
+- Register no tools yet.
+- Import no tool handlers yet.
+- Do not load config.
+- Do not call OpenAI.
+- Keep it minimal (~15 lines).
+
+**Smoke test:**
+```bash
+printf '%s\n' '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"smoke-test","version":"0.0.1"}}}' | npm start
+```
+
+Expected: process starts, no import/runtime crash, MCP initialize response returned with correct `serverInfo.name` and `serverInfo.version`.
+
+Status: ✅ Complete
+
+**What Task 5.1 established:**
+- MCP stdio server skeleton is operational.
+- MCP initialize handshake succeeds.
+- No tools registered yet — that belongs to Task 5.2.
+
+### Task 5.2 - Register ask_chatgpt MCP tool (NEXT)
diff --git a/src/server.js b/src/server.js
index 1669a24..9708c65 100644
--- a/src/server.js
+++ b/src/server.js
@@ -1 +1,9 @@
-// MCP stdio server entry point.
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+
+const server = new McpServer({
+  name: "chatgpt-mcp",
+  version: "0.1.0"
+});
+
+await server.connect(new StdioServerTransport());