renderdoc-mcp

MCP server for RenderDoc — let AI assistants analyze GPU frame captures (.rdc files) for graphics debugging and performance analysis.

Built on the Model Context Protocol, works with Claude Desktop, Claude Code, and any MCP-compatible client.

Features

• 42 tools covering the full RenderDoc analysis workflow
• 10 high-level tools for one-call analysis (draw call state, frame overview, diff, batch export, pixel region sampling, etc.)
• 3 built-in prompts for guided debugging
• Human-readable output — blend modes, depth functions, topology shown as names not numbers
• GPU quirk detection — auto-identifies Adreno/Mali/PowerVR/Apple-specific pitfalls from driver name
• Headless — no GUI needed, runs entirely via RenderDoc's Python replay API
• Pure Python — single pip install, no build step
• Supports D3D11, D3D12, OpenGL, Vulkan, OpenGL ES captures

Quick Start

1. Prerequisites

• Python 3.10+
• RenderDoc installed (download)
  • You need the renderdoc.pyd (Windows) or renderdoc.so (Linux) Python module
  • It ships with every RenderDoc installation

2. Install

git clone https://github.com/Linkingooo/renderdoc-mcp.git
cd renderdoc-mcp
pip install -e .

3. Find your renderdoc.pyd path

The Python module is in your RenderDoc install directory:

| Platform | Typical path | |----------|-------------| | Windows | C:\Program Files\RenderDoc\renderdoc.pyd | | Linux | /usr/lib/renderdoc/librenderdoc.so or where you built it |

You need the directory containing this file.

4. Configure your MCP client

{
  "mcpServers": {
    "renderdoc": {
      "command": "python",
      "args": ["-m", "renderdoc_mcp"],
      "env": {
        "RENDERDOC_MODULE_PATH": "C:\\Program Files\\RenderDoc"
      }
    }
  }
}

{
  "mcpServers": {
    "renderdoc": {
      "command": "python",
      "args": ["-m", "renderdoc_mcp"],
      "env": {
        "RENDERDOC_MODULE_PATH": "C:\\Program Files\\RenderDoc"
      }
    }
  }
}

# Set the module path
export RENDERDOC_MODULE_PATH="/path/to/renderdoc"   # Linux/macOS
set RENDERDOC_MODULE_PATH=C:\Program Files\RenderDoc  # Windows

# Run
python -m renderdoc_mcp

Usage Examples

Once configured, just talk to your AI assistant:

"Open frame.rdc and show me what's happening in the frame"

"Find the draw call that renders the character model and check its pipeline state"

"Why is my shadow map rendering black? Check the depth pass"

"Analyze performance — are there any redundant draw calls?"

Typical Tool Flow

open_capture("frame.rdc")                     # Load the capture
├── get_capture_info()                         # API, GPU, known_gpu_quirks
├── get_frame_overview()                       # Frame-level stats and render passes
├── get_draw_call_state(142)                   # Complete draw call state in one call
├── diff_draw_calls(140, 142)                  # Compare two draw calls (with implications)
├── export_draw_textures(142, "./tex/")        # Batch export all bound textures
├── save_render_target(142, "./rt.png")        # Save render target snapshot
├── analyze_render_passes()                    # Auto-detect render pass boundaries
├── find_draws(blend=True, min_vertices=1000)  # Search by rendering state
├── sample_pixel_region(rt_id, 0,0,512,512)   # Scan RT region for NaN/Inf/negatives
├── pixel_history(id, 512, 384)               # Debug a specific pixel
├── export_mesh(142, "./mesh.obj")             # Export mesh as OBJ
└── close_capture()                            # Clean up

For performance and diagnostic analysis:

get_pass_timing(granularity="pass")      # Find most expensive render passes
analyze_overdraw()                        # Fill-rate pressure estimate
analyze_bandwidth()                       # Memory bandwidth estimate
analyze_state_changes()                   # Batching opportunities
diagnose_negative_values()               # Find NaN/Inf/negative color values (爆闪)
diagnose_precision_issues()              # R11G11B10, D16, SRGB mismatches
diagnose_reflection_mismatch()           # Reflection artifact diagnosis
diagnose_mobile_risks()                  # Comprehensive mobile GPU risk check

For lower-level inspection, all granular tools remain available:

set_event(142)                                    # Navigate to a draw call
├── get_pipeline_state()                          # Inspect rasterizer/blend/depth
├── get_shader_bindings("pixel")                  # Check what textures/buffers are bound
├── get_cbuffer_contents("pixel", 0, filter="ibl") # Read shader constants (filterable)
├── disassemble_shader("pixel", search="SampleSH") # Shader code with context search
└── save_texture(id, "rt.png")                    # Export a specific texture

Tools

Session Management (4)

| Tool | Description | |------|-------------| | open_capture | Open a .rdc file (auto-closes previous) | | close_capture | Close current capture and free resources | | get_capture_info | Capture metadata: API, action count, resolution, known_gpu_quirks (Adreno/Mali/PowerVR/Apple) | | get_frame_overview | Frame-level statistics: action counts by type, texture/buffer memory, render targets, resolution |

Event Navigation (5)

| Tool | Description | |------|-------------| | list_actions | List the draw call / action tree — supports filter (name substring) and event_type (draw/clear/copy…) | | get_action | Full detail for a single action | | set_event | Navigate to an event (required before pipeline queries) | | search_actions | Search by name pattern and/or action flags | | find_draws | Search draw calls by rendering state: blend, min vertices, texture/shader/RT binding |

Pipeline Inspection (4)

| Tool | Description | |------|-------------| | get_pipeline_state | Full state: topology, viewports, rasterizer, blend, depth, stencil (human-readable enums) | | get_shader_bindings | Constant buffers, SRVs, UAVs, samplers for a shader stage | | get_vertex_inputs | Vertex attributes, vertex/index buffer bindings | | get_draw_call_state | One-call draw analysis: action info, blend formula, depth, stencil, rasterizer, textures with sizes, RTs, shaders |

Resource Analysis (4)

| Tool | Description | |------|-------------| | list_textures | All textures (filterable by format, min width) | | list_buffers | All buffers (filterable by min size) | | list_resources | All named resources (filterable by type, name pattern) | | get_resource_usage | Which events read/write a resource |

Data Extraction (8)

| Tool | Description | |------|-------------| | save_texture | Export to PNG, JPG, BMP, TGA, HDR, EXR, or DDS | | get_buffer_data | Read buffer bytes (hex dump or float32 array) | | pick_pixel | RGBA value at a coordinate | | get_texture_stats | Per-channel min/max/avg with anomaly detection (NaN/Inf/negative); supports all_slices for cubemaps | | read_texture_pixels | Read a rectangular region of pixels (up to 64×64) with per-pixel anomaly flags | | export_draw_textures | Batch export all textures bound to a draw call (auto-names, skips placeholders) | | save_render_target | Save RT snapshot at an event (color + optional depth) | | export_mesh | Export mesh as OBJ with positions, normals, UVs from post-VS data |

Shader Analysis (3)

| Tool | Description | |------|-------------| | disassemble_shader | Shader disassembly with auto fallback chain; supports search (keyword + context) and line_range | | get_shader_reflection | Input/output signatures, resource binding layout | | get_cbuffer_contents | Actual constant buffer variable values; supports filter for variable name substring |

Advanced (6)

| Tool | Description | |------|-------------| | pixel_history | Full per-pixel modification history across all events | | get_post_vs_data | Post-transform vertex data (VS out / GS out) | | diff_draw_calls | Compare two draw calls — shows state differences with human-readable implications | | analyze_render_passes | Auto-detect render pass boundaries by Clear/RT switches, summarize each pass | | sample_pixel_region | Uniform-grid scan of an RT region — detects NaN/Inf/negative/overexposed hotspots | | debug_shader_at_pixel | Per-pixel shader debug — returns variable trace or pixel value + shader info as fallback |

Performance Analysis (4)

| Tool | Description | |------|-------------| | get_pass_timing | Most expensive render passes — uses GPU counters if available, falls back to triangle-count heuristic | | analyze_overdraw | Overdraw estimate per render target group | | analyze_bandwidth | Write/read bandwidth estimate per render target | | analyze_state_changes | Finds redundant state-change patterns and batching opportunities |

Diagnostics (4)

| Tool | Description | |------|-------------| | diagnose_negative_values | Scans all float RTs for negative/NaN/Inf — finds first event introducing them, detects TAA accumulation | | diagnose_precision_issues | Checks R11G11B10 sign-bit loss, shallow depth buffers, SRGB/linear mismatches | | diagnose_reflection_mismatch | Compares reflection passes against main scene draws — finds shader/blend/format causes | | diagnose_mobile_risks | Comprehensive check across precision / performance / compatibility / GPU-specific risk categories |

Prompts

Built-in prompt templates to guide AI through common workflows:

| Prompt | Description | |--------|-------------| | debug_draw_call | Deep-dive a single draw call: pipeline → shaders → cbuffers → outputs | | find_rendering_issue | Systematic diagnosis from a problem description | | analyze_performance | Frame-wide perf analysis: pass timing, overdraw, bandwidth, state changes |

How It Works

AI Assistant ←—MCP—→ renderdoc-mcp server ←—Python API—→ renderdoc.pyd ←→ GPU replay

The server uses RenderDoc's headless replay API (renderdoc.pyd) to:

1. Open .rdc capture files without the GUI
2. Replay frames and query pipeline state at any event
3. Extract textures, buffers, shader data, and pixel history
4. Return structured JSON for the AI to reason about

Development

# Install in dev mode
pip install -e .

# Run tests (no RenderDoc needed — uses mocks)
python -m pytest tests/ -v

# Project structure
src/renderdoc_mcp/
├── server.py                 # FastMCP server, 3 prompt definitions
├── session.py                # Capture lifecycle, resource/texture caches (singleton)
├── util.py                   # Serialization, enum maps, blend formula, module loader
└── tools/
    ├── session_tools.py      # open/close/info (GPU quirks) + get_frame_overview
    ├── event_tools.py        # list/get/set/search actions + find_draws
    ├── pipeline_tools.py     # pipeline state, shader bindings, vertex inputs + get_draw_call_state
    ├── resource_tools.py     # texture/buffer/resource enumeration
    ├── data_tools.py         # save/read/pick/stats + read_texture_pixels + export_draw_textures, save_render_target, export_mesh
    ├── shader_tools.py       # disassembly (fallback chain, search), reflection, cbuffer contents (filter)
    ├── advanced_tools.py     # pixel history, post-VS data + diff_draw_calls (implications), analyze_render_passes, sample_pixel_region, debug_shader_at_pixel
    ├── performance_tools.py  # get_pass_timing, analyze_overdraw, analyze_bandwidth, analyze_state_changes
    └── diagnostic_tools.py  # diagnose_negative_values, diagnose_precision_issues, diagnose_reflection_mismatch, diagnose_mobile_risks

License

MIT