feat: register remaining MCP tools

TASKS.md

@@ -491,4 +491,39 @@ await server.connect(new StdioServerTransport());
 
 Status: ✅ Complete
 
-### Task 5.3 - Register remaining MCP tools (NEXT)
+### Task 5.3 - Register remaining MCP tools
+
+Register `review_plan`, `review_code`, `debug_issue`, and `architecture_review` as MCP tools on the server in `src/server.js`.
+
+**Requirements:**
+- Import four existing handlers: `handleReviewPlan`, `handleReviewCode`, `handleDebugIssue`, `handleArchitectureReview`.
+- Use `baseInputSchema` for all tool input schemas.
+- Explicitly register each tool with its own `registerTool()` call — no registry abstraction, no dynamic loop.
+- Pass all three deps (`loadConfig`, `createOpenAIClient`, `sendOpenAIResponse`) into each handler.
+- Return structured MCP tool result: `{ content: [{ type: "text", text }], isError, warnings }`.
+
+**Smoke test results (all passing):**
+
+| Test | Result |
+|------|--------|
+| initialize handshake | ✅ Server returns `chatgpt-mcp` v0.1.0 |
+| tools/list count | ✅ Returns 5 tools total |
+| all tool names present | ✅ ask_chatgpt, review_plan, review_code, debug_issue, architecture_review |
+| tools/call each tool (no API key) | ✅ Structured MCP error for all 5: `"Error: Configuration error: OPENAI_API_KEY is missing."` |
+| npm test | ✅ 523 tests pass across 18 test files — no regressions |
+
+**Production code (`src/server.js`) changes:**
+
+- Added imports: `handleReviewPlan`, `handleReviewCode`, `handleDebugIssue`, `handleArchitectureReview`
+- Added four `registerTool()` calls: `review_plan`, `review_code`, `debug_issue`, `architecture_review`
+- Existing `ask_chatgpt` registration unchanged
+- No new files created
+
+**SDK quirks noted:**
+
+1. `notifications/initialized` is not handled by the SDK — produces `-32601 Method not found`. Harmless.
+2. When `isError: true`, the SDK wraps results in a JSON-RPC error envelope (`{"error":{"code":-32603,...}}`) rather than a success result.
+
+Status: ✅ Complete
+
+### Task 5.4 - Normalize MCP tool error formatting (NEXT)