Tool

Description

Key Parameters

shader_debug_start

Starts an interactive debugging session for a compute dispatch, vertex draw, or fragment pixel.

captureId, commandIndex, stage ("compute", "vertex", "fragment"), entryPoint, code, shaderCaptureId, shaderObjectId, invocation, breakpoints, constants, sessionId

shader_debug_step

Advances shader execution by stepping lines or instructions.

sessionId, action ("step_next", "step_into", "step_over", "step_out"), count

shader_debug_continue

Continues execution until a line breakpoint is hit, the shader finishes, or maxSteps is reached.

sessionId, maxSteps (default: 50000)

shader_debug_set_breakpoints

Sets, removes, or clears line breakpoints in the active session.

sessionId, add (array of line numbers), remove (array of line numbers), clearAll (boolean)

shader_debug_get_stack

Returns the current callstack / call frames (innermost frame first) with function names and line numbers.

sessionId

shader_debug_get_variables

Inspects variables categorized by scope (locals, inputs, globals, constants, resources).

sessionId, scope ("all", "locals", "inputs", "globals", "constants", "resources"), filter, maxDepth

shader_debug_eval

Evaluates path expressions (e.g. in.position.x, uFrame.cameraPos.xyz, params.multiplier, matrix[1][2]).

sessionId, expression (or path)

shader_debug_stop

Stops and disposes an active debug session, freeing associated resources.

sessionId

Tool

Description

launch_browser

Launch a new instrumented Chrome/Edge instance via CDP.

attach_browser

Attach to an already-running Chrome/Edge on a remote debugging port.

open_page

Open a new instrumented tab in the controlled browser.

browser_status

Check browser connection and instrumented pages status.

list_pages

List connected WebGPU pages.

screenshot_page

Capture a composited PNG screenshot of the presented canvas/page.

capture_frames

Request frame capture from connected page with optional GPU profiling.

list_captures

List captures currently loaded in the store.

load_capture_file

Load a .wgpuc or .json capture file from disk.

get_capture_summary

Get high-level summary of passes, draw calls, objects, and validation errors.

analyze_performance

Profile GPU duration per pass and diagnose bottlenecks (fillrate vs ALU).

get_commands

Return paginated list of GPU commands in capture.

get_object

Inspect GPU object descriptor (buffers, textures, pipelines).

get_shader

Retrieve WGSL source code of a ShaderModule.

get_validation_errors

Get WebGPU validation errors recorded during capture.

get_draw_state

Resolve pipeline, bound vertex buffers, index buffers, and bind groups for a draw/dispatch.

decode_vertex_buffer

Decode captured vertex buffer payloads into typed attribute values.

diff_draws

Structurally diff the state between two draw calls.

read_buffer

Read live GPU buffer contents from connected page.

read_texture

Read live GPU texture / render target region and return statistics and ASCII view.

get_frame_stats

Sample live frame rate, frame time variance, and CPU submit cost.

Variable

Default

Description

WEBGPU_BRIDGE_CAPTURES_DIR

<cwd>/captures

Directory where uploaded .wgpuc frame captures are stored. If not set, it defaults to creating a captures/ folder in the current working directory. Setting an explicit absolute path keeps all captures in one dedicated location.

WEBGPU_BRIDGE_PORT

9690

Port for the local HTTP + WebSocket bridge that instrumented pages connect to. If the default port is already occupied by another session, the bridge automatically falls back to an OS-assigned free port.

WEBGPU_BRIDGE_HOST

127.0.0.1

Bind address for the local bridge server.

WEBGPU_BRIDGE_CHROME

(auto-detected)

Custom binary path for Google Chrome, Chromium, or Microsoft Edge. Auto-detects standard system paths if omitted.

WEBGPU_BRIDGE_TOKEN

(none)

Optional auth token required for instrumented pages to connect to the bridge.

WEBGPU_INSPECTOR_SCRIPT

(bundled)

Path or URL to custom webgpu_inspector.js injection script. Defaults to the bundled file.