MCP Servers

A collection of Model Context Protocol servers, templates, tools and more.

F
Flutter Profile MCP
by @cybersleuth0
GitHub Repo(1 stars)

MCP server for Flutter performance profiling — 26 AI-queryable tools via vm_service. Ask Claude why your app is slow.

Created 5/28/2026
Updated about 7 hours ago
README
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Repository documentation and setup instructions

flutter_profile_mcp

An MCP (Model Context Protocol) server that connects to a running Flutter app via vm_service and exposes 27 performance, memory, and debugging tools as AI-queryable actions.

Ask Claude or Gemini "why is my app slow?" and get an actual diagnosis — not generic advice.

What it does

Flutter DevTools is powerful but hard to use. This MCP server bridges the gap: it speaks directly to the Dart VM, collects the same data DevTools collects, and translates it into plain English that an AI agent can reason about and explain.

You:    "Why is my app slow?"

AI:     [calls connect_to_app]
        Connected. VM 3.11 | isolate: main | debug mode | iOS arm64

        [calls capture_frame_timing duration=5]
        Frame Analysis — 198 frames (~38.4 fps) via Flutter.Frame events
        Budget: 16ms at 60fps
        ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
        Janky: 0/198 (0.0%) — GOOD
        Worst frame: 4.54ms work (Build: 2.92ms, Raster: 1.61ms)

        [calls get_widget_rebuild_counts duration=8]
        Widget Rebuild Counts:
        ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
          Text (patient_dashboard.dart:142)       62 rebuilds  ← EXCESSIVE
          SizedBox (patient_dashboard.dart:98)    60 rebuilds  ← EXCESSIVE
          SlideTransition (app_wrapper.dart:31)   29 rebuilds  ← HIGH
          BlocProvider (main.dart:44)             26 rebuilds  ← HIGH

        Animation widgets rebuilding (possible idle animation leak):
          SlideTransition (app_wrapper.dart:31): 29 rebuilds
          → ensure AnimationController.dispose() called

        [calls get_cpu_hotspots duration=5]
        CPU Hotspots (5.0s window, 678 samples)
        ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
          1.  1.6%   13.3%  RenderObject._paintWithContext
          2.  1.1%    1.3%  Duration.Duration

        Suggestions:
        • RenderObject._paintWithContext: 13.3% total — expensive call chain. Check callees.

Requirements

  • Flutter app running in debug or profile mode (flutter run or flutter run --profile)
  • Dart SDK ≥ 3.4.0
  • Any MCP-compatible client (Claude Desktop, Claude Code, Gemini CLI, etc.)

Installation

Option A — pub.dev (recommended, no git clone needed)

dart pub global activate flutter_profile_mcp

This installs the flutter-profile-mcp command globally. Use this path in your MCP config:

which flutter-profile-mcp
# e.g. /Users/you/.pub-cache/bin/flutter-profile-mcp

Option B — compile from source

git clone https://github.com/cybersleuth0/flutter-profile-mcp
cd flutter-profile-mcp
dart pub get
dart compile exe bin/flutter_devtools_mcp.dart -o flutter_devtools_mcp

Option C — run directly with Dart

git clone https://github.com/cybersleuth0/flutter-profile-mcp
cd flutter-profile-mcp
dart pub get

Claude Desktop setup

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS):

{
  "mcpServers": {
    "flutter-profile": {
      "command": "flutter-profile-mcp"
    }
  }
}

Note: flutter-profile-mcp must be on your PATH. Run dart pub global activate flutter_profile_mcp first, then verify with which flutter-profile-mcp.

Restart Claude Desktop after editing.

Claude Code / Gemini CLI setup

Add to your project's .claude/settings.json or ~/.gemini/settings.json:

{
  "mcpServers": {
    "flutter-profile": {
      "command": "flutter-profile-mcp"
    }
  }
}

Usage

  1. Run your Flutter app: flutter run
  2. Copy the VM service URI from terminal output — looks like ws://127.0.0.1:PORT/TOKEN=/ws
  3. Tell the AI: "Connect to my Flutter app at <uri>"
  4. Ask anything:
    • "Why is my app slow? Capture 5 seconds while I scroll."
    • "Which widgets rebuild too often?"
    • "Are there any memory leaks?"
    • "Show me recent HTTP requests."
    • "What errors appeared in the last 5 seconds?"

Tools (27)

Connection

| Tool | Description | |------|-------------| | connect_to_app | Connect to running Flutter app via VM service URI | | get_app_info | Flutter/Dart version, build mode, isolates, all registered service extensions |

Performance

| Tool | Description | |------|-------------| | capture_frame_timing | Record frame times via Flutter.Frame stream, detect jank (>16ms), identify UI vs raster bottleneck | | get_cpu_hotspots | CPU profile — top Dart functions by self-time and call-chain cost, with fix suggestions | | get_widget_rebuild_counts | Track which widgets rebuild excessively with file:line context — the #1 cause of jank | | analyze_jank_causes | Composite: frames + CPU → synthesized verdict + prioritized diagnosis | | enable_performance_overlay | Toggle on-screen GPU/UI thread bars | | debug_frame_events | Inspect raw timeline event names — use when frame capture returns 0 frames |

Memory

| Tool | Description | |------|-------------| | get_memory_usage | Heap usage + top allocating classes | | get_memory_timeline | Record heap + GC events over N seconds — detects growing heap | | force_gc | Trigger GC, compare before/after — high retained = leak signal | | diff_memory_snapshots | Snapshot A → interact → snapshot B → show class growers | | find_memory_leaks | Automated: GC → baseline → observe → GC → measure → leak candidates | | get_class_instances | Instance count + size for any class by name | | watch_gc_pressure | GC rate + avg pause → NORMAL / ELEVATED / CRITICAL verdict | | explain_memory_breakdown | RSS vs Dart heap vs external vs raster in plain English | | disable_http_logging | Disable HTTP logging to reduce memory overhead during profiling |

Logging

| Tool | Description | |------|-------------| | watch_logs | Stream stdout/stderr/debugPrint for N seconds with optional filter | | get_error_logs | Capture N seconds of output, return only error/exception lines |

Network

| Tool | Description | |------|-------------| | get_http_profile | Recent HTTP requests with method, status, timing, size | | watch_network | Live-stream new HTTP requests as they happen | | get_http_request_body | Full request/response headers for a specific request ID |

Navigation & Isolates

| Tool | Description | |------|-------------| | get_navigation_stack | Current route + full navigation stack — detect route leaks | | list_isolates | All running isolates with heap usage |

Visual Debugging

| Tool | Description | |------|-------------| | toggle_visual_debug | debug_paint (widget bounds) + repaint_rainbow (overdraw detection) |

Code Evaluation

| Tool | Description | |------|-------------| | eval_expression | Evaluate Dart expression in live app context |

Developer Workflow

| Tool | Description | |------|-------------| | hot_reload | Trigger hot reload — apply source changes without restarting | | get_widget_tree | Full widget hierarchy as readable indented tree |

Debug vs Profile mode

| Mode | Command | What works | |------|---------|------------| | Debug | flutter run | All 27 tools including widget inspector, rebuild counts | | Profile | flutter run --profile | Performance tools (accurate numbers, no debug overhead) | | Release | flutter run --release | Nothing — VM service not available |

For accurate frame/CPU numbers, use profile mode. For widget tree and rebuild tracking, use debug mode.

How frame timing works

capture_frame_timing uses the Flutter.Frame extension event stream — the same source as Flutter DevTools' Performance tab. Flutter emits one event per frame containing pre-computed build, raster, and elapsed (wall time including vsync wait) in microseconds.

Jank is measured on build + raster (actual CPU/GPU work), not elapsed. elapsed always includes vsync idle time (~16ms at 60fps) which would make every frame appear janky.

Architecture

flutter-profile-mcp/
├── bin/
│   └── flutter_devtools_mcp.dart     # Entry point — stdio MCP transport
├── lib/
│   ├── server.dart                   # MCPServer — all 27 tools registered
│   └── analysis/
│       ├── jank_analyzer.dart        # Flutter.Frame stream → frame data → jank report
│       ├── cpu_analyzer.dart         # CpuSamples → hotspot report (handles dynamic fn field)
│       └── rebuild_collector.dart    # RebuiltWidgets events → rebuild counts with file:line

Built with:

Contributing

Tool ideas, bug reports, and PRs welcome.

To add a new tool:

  1. Register it in _registerTools() in lib/server.dart
  2. Add a _handleXxx() handler method
  3. Use _service!.callServiceExtension() for Flutter extensions or direct VmService methods
  4. Return _ok(text) on success, _err(e) on failure

License

MIT — see LICENSE

Quick Setup
Installation guide for this server

Installation Command (package not published)

git clone https://github.com/cybersleuth0/flutter-profile-mcp
Manual Installation: Please check the README for detailed setup instructions and any additional dependencies required.

Cursor configuration (mcp.json)

{ "mcpServers": { "cybersleuth0-flutter-profile-mcp": { "command": "git", "args": [ "clone", "https://github.com/cybersleuth0/flutter-profile-mcp" ] } } }