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

<details> <summary><b>Claude Desktop</b></summary>

Edit claude_desktop_config.json (Settings → Developer → Edit Config):

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

</details>

<details> <summary><b>Claude Code</b></summary>

Add to .claude/settings.json:

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

</details>

<details> <summary><b>Run standalone</b></summary>

# 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

</details>

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