feat: add token optimization parameters (maxLength, selector, image resizing)#833
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semikolon wants to merge 5 commits intoChromeDevTools:mainfrom
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feat: add token optimization parameters (maxLength, selector, image resizing)#833semikolon wants to merge 5 commits intoChromeDevTools:mainfrom
semikolon wants to merge 5 commits intoChromeDevTools:mainfrom
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Inspired by fast-playwright-mcp, this adds foundation for token-efficient responses: - Add expectation.ts with schema for controlling response content - includeSnapshot, includeConsole, includeNetwork, includeTabs - snapshotOptions (selector, maxLength, verbose) - imageOptions (quality, maxWidth, maxHeight, format) - Tool-specific defaults for optimal token usage - Add maxLength truncation to SnapshotFormatter - Truncates snapshot output with notice when limit exceeded - Useful for token efficiency on large pages - Expose maxLength parameter in take_snapshot tool - Users can now limit snapshot size directly This is Phase 1 of token optimization - the infrastructure layer. Future phases can integrate the expectation schema into tool handlers and add image processing utilities. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Document the fork's token optimization features: - Snapshot truncation via maxLength parameter - Future enhancement infrastructure (expectation schema) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
…ation Phase 2 of token optimization implementation: Snapshot CSS selector filtering: - Added `selector` parameter to take_snapshot tool - Filters snapshot to only include subtree matching CSS selector - Uses CDP DOM.describeNode to map elements to accessibility nodes - Falls back to full snapshot with warning if selector doesn't match Screenshot image resizing: - Added `maxWidth` and `maxHeight` parameters to take_screenshot - Images resized maintaining aspect ratio using sharp library - Logs compression ratio when resizing occurs - Added sharp as production dependency Code changes: - src/utils/image-processor.ts: New utility for image processing - src/McpResponse.ts: Added #filterSnapshotBySelector private method - src/tools/screenshot.ts: Integrated image resizing - src/tools/snapshot.ts: Added selector parameter - src/tools/ToolDefinition.ts: Extended SnapshotParams with selector Documentation: - Updated README with full token optimization documentation - Added parameter reference table for all optimization options Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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This was referenced Jan 25, 2026
semikolon
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Jan 25, 2026
- Added "Browser MCP Selection" section with fork recommendation - Updated comparison table to include CDT Fork column - Removed outdated "Both: Doesn't exist yet" - it now exists! - Removed redundant Playwright GPU config (use --autoConnect instead) - Updated fast-playwright-mcp section to reference the fork Fork: https://github.com/semikolon/chrome-devtools-mcp PR: ChromeDevTools/chrome-devtools-mcp#833 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Add maxLength truncation tests to snapshotFormatter.test.ts - Add new image-processor.test.ts with tests for resize and format conversion - Use sharp to generate valid test images (more reliable than manual PNG bytes) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- maxWidth, maxHeight for take_screenshot - maxLength, selector for take_snapshot - Format fixes from prettier Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Jan 30, 2026
| .describe( | ||
| 'The absolute path, or a path relative to the current working directory, to save the snapshot to instead of attaching it to the response.', | ||
| ), | ||
| maxLength: zod |
Collaborator
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max length does not seem like a good parameter for tree structures.
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| // Apply selector filtering if specified | ||
| if (textSnapshot && this.#snapshotParams.selector) { | ||
| const filteredSnapshot = await this.#filterSnapshotBySelector( |
Collaborator
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I think this might not work as expected, we would need more tests for different scenarios of getting filtered snapshots and using uids from the current and the past snapshots.
| return null; | ||
| } | ||
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| // Get the backendNodeId via CDP |
Collaborator
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I believe backendNodeId is a public API in puppeteer https://pptr.dev/api/puppeteer.elementhandle.backendnodeid
| * Process an image with optional resizing and format conversion. | ||
| * Returns the processed image buffer and metadata. | ||
| */ | ||
| export async function processImage( |
Collaborator
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We should not include image processing in the same PR as the snapshot work. Additionally, I do not think we plan to have any image processing capabilities right now.
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Summary
Adds token optimization features inspired by fast-playwright-mcp, addressing concerns raised in #340, #726, and #716.
Changes
Snapshot optimization
maxLengthparameter - truncates snapshot with notice when exceededselectorparameter - limits snapshot to CSS selector subtree (addresses Accessibility tree/snapshot for a specific DOM element, including whole hierarchy below it (custom "root" element) #716)Screenshot optimization
maxWidth/maxHeightparameters - resizes images maintaining aspect ratiosharplibrary for image processingFiles changed
src/tools/snapshot.ts- added maxLength, selector paramssrc/tools/screenshot.ts- added maxWidth, maxHeight paramssrc/utils/image-processor.ts- new image processing utilitysrc/McpResponse.ts- selector filtering logicsrc/tools/ToolDefinition.ts- extended SnapshotParamsToken savings
These features allow agents to dramatically reduce context usage on large pages by: