We scan this tool’s changelog a few times a day and keep the changes that would alter your agent’s next action: 51 since January 2026, each linked to its source.
chrome-devtools-mcpWhen diagnosing retained memory from a heap snapshot, use `analyze_heapsnapshot_contexts` to rank closure contexts holding dead captured fields; it requires `--memoryDebugging=true`. The retained-size score is a prioritizing heuristic, not an exact measure of reclaimable bytes.
analyze_heapsnapshot_contexts({"filePath":"<path-to-file.heapsnapshot>"})When reviewing a large comparison, call `compare_heapsnapshots` with the two snapshot paths and `pageIdx`/`pageSize`; the summary diff returns the requested class page with indexes and an overall class total.
compare_heapsnapshots({"baseFilePath":"<earlier-snapshot.heapsnapshot>","currentFilePath":"<later-snapshot.heapsnapshot>","pageIdx":0,"pageSize":20})When checking a page’s accessibility or motion preferences, call `emulate` with the desired media feature value(s). Set any feature to `auto` to reset it; include all desired emulation settings in one call because each call replaces them.
{"pageId": <pageId>, "forcedColors": "active"}When evaluating repository JavaScript in a target page, pass its local file path with `--sourcePath` and choose `--format` for how to interpret the source. Provide `sourcePath` or `function`, never both.
chrome-devtools evaluate_script --pageId 1 --sourcePath /path/to/script.js --format scriptWhen inspecting a heap snapshot, call `get_heapsnapshot_details` with the snapshot path and optional `maxNameLength` to truncate long names (default 100). Read `className` in CSV output and `heapSnapshotAggregates` in structured content; aggregate sizes are raw bytes.
get_heapsnapshot_details({"filePath":"<path-to-heapsnapshot>","maxNameLength":100})For a cold page-load trace, first navigate to the target URL, then call `performance_start_trace` with `reload: true` and `ignoreCache: true`.
performance_start_trace({"pageId": <pageId>, "reload": true, "ignoreCache": true})When recording a page without ffmpeg, call `screencast_start` and then `screencast_stop`; the built-in recorder writes MP4. To set the frame rate, configure `--screencast-fps=<positive-integer>` (the old `--experimental-screencast-fps` name remains an alias).
screencast_start({"pageId": <page-id>, "filePath": "<output.mp4>"})
screencast_stop({"pageId": <page-id>})When a page exposes WebMCP tools, enable the WebMCP category and Chrome’s WebMCP feature; enable the third-party category to list and execute tools marked `annotations.debugging === true`. Use the regular WebMCP tools for other WebMCP tools.
list_3p_developer_tools({"pageId": <pageId>}) → execute_3p_developer_tool({"pageId": <pageId>, "toolName": "<toolName>", "params": "<JSON-stringified parameters>"})When configuring chrome-devtools-mcp for a repository workflow, put the desired server options in a JSON object and pass its path with `--config` when starting the server.
npx -y chrome-devtools-mcp@1.10.0 --config <path-to-config.json>When debugging why an element’s styles apply, are overridden, or conflict, get its UID from `take_snapshot`, then call `get_css_styles` with the page ID and UID. Page through results with `pageIdx`; each page returns 10 rules by default.
chrome-devtools get_css_styles <pageId> "<uid>"