Stata MCP Server

# Streaming Output Solution for Claude Code ## Problem Statement We want Stata output to appear **progressively in Claude Code** as it's generated, not just when execution completes. ## Current Situation ✅ **Server already sends progressive updates:** - Reads Stata log file every 6 seconds - Sends snippets via `send_log_message()` - All notifications successfully sent via SSE ❌ **Claude Code doesn't display them:** - No logging callback registered - Notifications sent but not shown to user ## MCP Protocol Limitations **MCP tools cannot stream responses.** From the MCP specification: - Tool calls must return a single, final result - No mechanism for partial/progressive results - Tool response is atomic (all-or-nothing) ## Available MCP Mechanisms ### 1. Notifications (Current Approach) ```python await session.send_log_message( level="notice", data="📝 Output: iteration 10 completed", logger="stata-mcp" ) ``` **Status:** ✅ Implemented, ❌ Claude Code doesn't display ### 2. Progress Notifications ```python await session.send_progress_notification( progress_token=token, progress=elapsed, total=timeout, message="Current output..." ) ``` **Status:** ❌ Claude Code doesn't send `progressToken` ### 3. Resources (Not Applicable) - Resources are for static/semi-static content - Not designed for real-time streaming - Would require Claude Code to poll repeatedly ## The Real Issue **This is a Claude Code limitation, not an MCP or server limitation.** Claude Code needs to: 1. Register a `logging_callback` to receive notifications, OR 2. Provide a `progressToken` to receive progress updates, OR 3. Implement a custom streaming mechanism None of these are currently happening. ## Possible Solutions ### Solution 1: Wait for Claude Code Fix (Recommended) **Action:** File bug report with Anthropic **Evidence to include:** - MCP Python SDK successfully receives all 26 notifications - Server logs show notifications being sent - Claude Code receives SSE stream but doesn't display **Timeline:** Unknown (depends on Anthropic) ### Solution 2: Alternative Display Method Since we can't stream to Claude Code's UI, we could: **A. Include progressive output in final response:** ```python # Accumulate output during execution accumulated_output = [] while not task.done(): # Read new output new_output = read_stata_log() accumulated_output.append(new_output) # Send as notification (won't display, but logged) await send_log("notice", new_output) # Return ALL accumulated output in final result return {"output": "\n".join(accumulated_output)} ``` **Status:** ✅ Already doing this (final response includes all output) **B. Web-based viewer:** - Serve Stata output via HTTP endpoint - Provide URL in tool response - User opens browser to see live output **C. File-based monitoring:** - Tell user where log file is - User can `tail -f` the log file ### Solution 3: Custom Claude Code Extension If Claude Code supports extensions/plugins, we could: 1. Create a Claude Code extension 2. Extension registers logging callback 3. Extension displays notifications in custom UI **Status:** Unknown if Claude Code supports this ## Recommendation ### Short Term **Accept current limitation and document it:** ```markdown ## Known Limitation Due to a Claude Code client limitation, Stata output is only displayed after execution completes. Progress notifications are sent by the server but not currently displayed by Claude Code. **Workaround:** Monitor the log file directly: ```bash tail -f ~/.vscode/extensions/deepecon.stata-mcp-*/logs/your_script_mcp.log ``` ### Medium Term **File bug report with Anthropic:** Title: "Claude Code doesn't display MCP logging notifications" Description: - MCP servers can send `notifications/message` during tool execution - Claude Code receives these (verified in network logs) - Claude Code doesn't display them to users - Other MCP clients (Python SDK) work correctly Expected: Notifications should appear in Claude Code UI Actual: Only final tool result is shown ### Long Term **When Claude Code is fixed:** - No server changes needed! - Our implementation already sends progressive updates - Will automatically work when Claude Code registers logging callback ## Testing Evidence ### Proof Notifications Are Sent ``` Server Log: 2025-10-23 19:32:13 - MCP streaming log: ⏱️ 6s elapsed 2025-10-23 19:32:13 - sse_starlette.sse - chunk: event: message data: {"method":"notifications/message","params":{"level":"notice","data":"⏱️ 6s..."}} ``` ### Proof They Can Be Received ``` MCP Python SDK Test: 📢 [0.0s] Log [notice]: ▶️ Starting Stata execution 📢 [6.0s] Log [notice]: ⏱️ 6s elapsed - iteration 6 ... (26 notifications total) ✅ SUCCESS: All notifications received! ``` ### Proof Claude Code Doesn't Display Them ``` Claude Code UI: (blank during execution) (only shows final result after 72 seconds) ``` ## Conclusion **The server is working correctly.** We: - ✅ Read Stata log progressively - ✅ Send updates every 6 seconds - ✅ Include recent output snippets - ✅ Use correct MCP protocol - ✅ Verified with MCP Python SDK **The issue is in Claude Code.** It needs to register a callback to receive and display the notifications we're already sending. **No server changes can fix this** - it must be fixed in Claude Code's client implementation.