dialog-reddit-tools

# FastMCP Context API Implementation Summary **Status:** ✅ Complete **Date:** 2025-10-02 **Phases Completed:** Phase 1 (Context Integration) + Phase 2 (Progress Monitoring) ## Overview This document summarizes the completed implementation of FastMCP's Context API integration into the Reddit MCP server. The implementation was completed in two phases and enables real-time progress reporting for long-running Reddit operations. ## Phase 1: Context Integration (Complete ✅) ### Goal Integrate FastMCP's `Context` parameter into all tool and operation functions to enable future context-aware features. ### Implementation Details **Scope:** All MCP tool functions and Reddit operation functions now accept `Context` as a parameter. #### Functions Updated - ✅ `discover_subreddits()` - Subreddit discovery via vector search - ✅ `search_in_subreddit()` - Search within specific subreddit - ✅ `fetch_subreddit_posts()` - Fetch posts from single subreddit - ✅ `fetch_multiple_subreddits()` - Batch fetch from multiple subreddits - ✅ `fetch_submission_with_comments()` - Fetch post with comment tree - ✅ `validate_subreddit()` - Validate subreddit exists in index - ✅ `_search_vector_db()` - Internal vector search helper - ✅ `parse_comment_tree()` - Internal comment parsing helper #### MCP Layer Functions - ✅ `discover_operations()` - Layer 1: Discovery - ✅ `get_operation_schema()` - Layer 2: Schema - ✅ `execute_operation()` - Layer 3: Execution ### Test Coverage - **8 integration tests** verifying context parameter acceptance - All tests verify functions accept `Context` without errors - Context parameter can be positioned anywhere in function signature ### Files Modified (Phase 1) 1. `src/tools/discover.py` - Added `ctx: Context = None` to all functions 2. `src/tools/search.py` - Added context parameter 3. `src/tools/posts.py` - Added context parameter 4. `src/tools/comments.py` - Added context parameter and forwarding 5. `src/server.py` - Updated MCP tools to accept and forward context 6. `tests/test_context_integration.py` - Created comprehensive test suite --- ## Phase 2: Progress Monitoring (Complete ✅) ### Goal Add real-time progress reporting to long-running Reddit operations using `ctx.report_progress()`. ### Implementation Details **Scope:** Three primary long-running operations now emit progress events. #### Operation 1: `discover_subreddits` - Vector Search Progress **File:** `src/tools/discover.py` **Progress Events:** - Reports progress for each subreddit analyzed during vector search - **Message Format:** `"Analyzing r/{subreddit_name}"` - **Frequency:** 10-100 events depending on `limit` parameter - **Progress Values:** `progress=i+1, total=total_results` **Implementation:** ```python async def _search_vector_db(...): total_results = len(results['metadatas'][0]) for i, (metadata, distance) in enumerate(...): if ctx: await ctx.report_progress( progress=i + 1, total=total_results, message=f"Analyzing r/{metadata.get('name', 'unknown')}" ) ``` #### Operation 2: `fetch_multiple_subreddits` - Batch Fetch Progress **File:** `src/tools/posts.py` **Progress Events:** - Reports progress when encountering each new subreddit - **Message Format:** `"Fetching r/{subreddit_name}"` - **Frequency:** 1-10 events (one per unique subreddit) - **Progress Values:** `progress=len(processed), total=len(subreddit_names)` **Implementation:** ```python async def fetch_multiple_subreddits(...): processed_subreddits = set() for submission in submissions: subreddit_name = submission.subreddit.display_name if subreddit_name not in processed_subreddits: processed_subreddits.add(subreddit_name) if ctx: await ctx.report_progress( progress=len(processed_subreddits), total=len(clean_names), message=f"Fetching r/{subreddit_name}" ) ``` #### Operation 3: `fetch_submission_with_comments` - Comment Tree Progress **File:** `src/tools/comments.py` **Progress Events:** - Reports progress during comment loading - Final completion message when done - **Message Format:** - During: `"Loading comments ({count}/{limit})"` - Complete: `"Completed: {count} comments loaded"` - **Frequency:** 5-100+ events depending on `comment_limit` - **Progress Values:** `progress=comment_count, total=comment_limit` **Implementation:** ```python async def fetch_submission_with_comments(...): for top_level_comment in submission.comments: if ctx: await ctx.report_progress( progress=comment_count, total=comment_limit, message=f"Loading comments ({comment_count}/{comment_limit})" ) # ... process comment # Final completion if ctx: await ctx.report_progress( progress=comment_count, total=comment_limit, message=f"Completed: {comment_count} comments loaded" ) ``` ### Async/Await Changes All three operations are now **async functions**: - ✅ `discover_subreddits()` → `async def discover_subreddits()` - ✅ `fetch_multiple_subreddits()` → `async def fetch_multiple_subreddits()` - ✅ `fetch_submission_with_comments()` → `async def fetch_submission_with_comments()` - ✅ `execute_operation()` → `async def execute_operation()` (conditionally awaits async operations) ### Test Coverage **New Test Classes (Phase 2):** 1. `TestDiscoverSubredditsProgress` - Verifies progress during vector search 2. `TestFetchMultipleProgress` - Verifies progress per subreddit 3. `TestFetchCommentsProgress` - Verifies progress during comment loading **Test Assertions:** - ✅ Progress called minimum expected times (based on data) - ✅ Progress includes `progress` and `total` parameters - ✅ AsyncMock properly configured for async progress calls **Total Test Results:** 18 tests, all passing ✅ ### Files Modified (Phase 2) 1. `src/tools/discover.py` - Made async, added progress reporting 2. `src/tools/posts.py` - Made async, added progress reporting 3. `src/tools/comments.py` - Made async, added progress reporting 4. `src/tools/search.py` - No changes (operation too fast for progress) 5. `src/server.py` - Made `execute_operation()` async with conditional await 6. `tests/test_context_integration.py` - Added 3 progress test classes 7. `tests/test_tools.py` - Updated 3 tests to handle async functions 8. `pyproject.toml` - Added pytest asyncio configuration --- ## Current MCP Server Capabilities ### Context API Support **All operations support:** - ✅ Context parameter injection via FastMCP - ✅ Progress reporting during long operations - ✅ Future-ready for logging, sampling, and other context features ### Progress Reporting Patterns **For Frontend/Client Implementation:** 1. **Vector Search (discover_subreddits)** - Progress updates: Every result analyzed - Typical range: 10-100 progress events - Pattern: Sequential 1→2→3→...→total - Message: Subreddit name being analyzed 2. **Multi-Subreddit Fetch (fetch_multiple)** - Progress updates: Each new subreddit encountered - Typical range: 1-10 progress events - Pattern: Incremental as new subreddits found - Message: Subreddit name being fetched 3. **Comment Tree Loading (fetch_comments)** - Progress updates: Each comment + final completion - Typical range: 5-100+ progress events - Pattern: Sequential with completion message - Message: Comment count progress ### FastMCP Progress API Specification **Progress Call Signature:** ```python await ctx.report_progress( progress: float, # Current progress value total: float, # Total expected (enables percentage) message: str # Optional descriptive message ) ``` **Client Requirements:** - Clients must send `progressToken` in initial request to receive updates - If no token provided, progress calls have no effect (won't error) - Progress events sent as MCP notifications during operation execution --- ## Integration Notes for Frontend Agent ### Expected Behavior 1. **Progress Events are Optional** - Operations work without progress tracking - Progress enhances UX but isn't required for functionality 2. **Async Operation Handling** - All three operations are async and must be awaited - `execute_operation()` properly handles both sync and async operations 3. **Message Patterns** - Messages are descriptive and user-friendly - Include specific subreddit names and counts - Can be displayed directly to users ### Testing Progress Locally **To test progress reporting:** 1. Use MCP Inspector or Claude Desktop (supports progress tokens) 2. Call operations with realistic data sizes: - `discover_subreddits`: limit=20+ for visible progress - `fetch_multiple`: 3+ subreddits for multiple events - `fetch_comments`: comment_limit=50+ for visible progress ### Known Limitations 1. **Single-operation Progress Only** - No multi-stage progress across multiple operations - Each operation reports independently 2. **No Progress for Fast Operations** - `search_in_subreddit`: Too fast, no progress - `fetch_subreddit_posts`: Single subreddit, too fast 3. **Progress Granularity** - Vector search: Per-result (can be 100+ events) - Multi-fetch: Per-subreddit (typically 3-10 events) - Comments: Per-comment (can be 100+ events) --- ## Future Enhancements (Not Yet Implemented) **Phase 3: Structured Logging** (Planned) - Add `ctx.info()`, `ctx.debug()`, `ctx.warning()` calls - Log operation start/end, errors, performance metrics **Phase 4: Enhanced Error Handling** (Planned) - Better error context via `ctx.error()` - Structured error responses with recovery suggestions **Phase 5: LLM Sampling** (Planned) - Use `ctx.sample()` for AI-enhanced subreddit suggestions - Intelligent query refinement based on results --- ## API Surface Summary ### Async Operations (Require await) ```python # These are now async await discover_subreddits(query="...", ctx=ctx) await fetch_multiple_subreddits(subreddit_names=[...], reddit=client, ctx=ctx) await fetch_submission_with_comments(reddit=client, submission_id="...", ctx=ctx) await execute_operation(operation_id="...", parameters={...}, ctx=ctx) ``` ### Sync Operations (No await) ```python # These remain synchronous search_in_subreddit(subreddit_name="...", query="...", reddit=client, ctx=ctx) fetch_subreddit_posts(subreddit_name="...", reddit=client, ctx=ctx) ``` ### Progress Event Format **Client receives progress notifications:** ```json { "progress": 15, "total": 50, "message": "Analyzing r/Python" } ``` **Percentage calculation:** ```javascript const percentage = (progress / total) * 100; // 30% in example ``` --- ## Validation & Testing ### Test Suite Results - ✅ **18 total tests** (all passing) - ✅ **11 context integration tests** (8 existing + 3 new progress) - ✅ **7 tool tests** (updated for async) - ✅ No breaking changes to existing API - ✅ No performance degradation ### Manual Testing Checklist - ✅ Vector search reports progress for each result - ✅ Multi-subreddit fetch reports per subreddit - ✅ Comment loading reports progress + completion - ✅ Progress messages are descriptive - ✅ Operations work without context (graceful degradation) --- ## References - [FastMCP Context API Docs](../ai-docs/fastmcp/docs/servers/context.mdx) - [FastMCP Progress Reporting Docs](../ai-docs/fastmcp/docs/servers/progress.mdx) - [Phase 1 Spec](./003-phase-1-context-integration.md) - [Phase 2 Spec](./003-phase-2-progress-monitoring.md) - [Master Integration Spec](./003-fastmcp-context-integration.md)