feat: add token optimization parameters (maxLength, selector, image resizing) #833
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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
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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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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: