Playwright Trace Decoder MCP

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npx agentmarket install connector/vola-trebla-playwright-trace-decoder-mcp

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What this server can do and what it asks for, from its tool list and install config. Checked Oct 25, 2026.

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Tools (19)

Read from the source code; the running server may differ. Descriptions are the server’s own words; hidden characters are shown as [U+…].

• analyze_race_conditions

  Detects potential race conditions by finding network requests that were still in-flight when a user interaction action fired. Returns flagged actions with pending requests.

• compare_traces

  Compares a passing and a failing trace of the same test. Aligns actions by sequence, finds the first timing or structural divergence, and summarises network differences. Use to diagnose flakiness — what was different in the run that failed.

• correlate_dom_and_network

  Joins the HAR network log and DOM snapshots into an explicit causal chain. For each action where a network response completed and the DOM mutated within ±100ms, returns the triggering request URL, response status, body snippet, and the exact DOM nodes that appeared or disappeared. Background polling and analytics pixels are filtered out. Use to diagnose race conditions and async rendering bugs — removes hallucination from the question 'did this fetch cause this DOM change?'

• detect_performance_anomalies

  Detects Long Tasks and frame drops that cause Playwright timeouts. Analyses screencast-frame timestamps for main-thread blocking (gaps > 50ms), flags actions that took longer than 500ms, counts concurrent in-flight network requests during each slow action, and checks for monotonically increasing action durations (suspected memory leak). Returns a ranked list of anomalies with a suspected_cause so the agent can distinguish a blocked main thread from network saturation or a navigation timeout — without blaming a missing element.

• extract_critical_frames

  Extracts key screencast screenshots (base64 JPEG) from a temporal window around a test failure or the end of the trace, resolved with their associated test step titles.

• extract_trace_metadata_strict

  Strictly inspects a Playwright trace archive and returns format version, retry session breakdown, and HAR payload mode. Handles .pwtrace.zip extensions (newer Playwright CI), multi-retry archives (identifies which retry failed), and all three HAR modes: embed (bodies inline), attach (bodies as separate files), omit (headers only). Use before other trace tools when the archive may be from an unfamiliar Playwright version or CI configuration — confirms the trace is valid and tells you what data is available.

• generate_error_signature

  Generates a stable 12-char hash signature for a test failure by normalizing the error message (stripping paths, numbers, UUIDs). Use to group duplicate failures across parallel CI runs without reading each trace manually.

• get_action_timeline

  Returns a paginated timeline of all actions with locators and timings. Use limit/offset to page through large traces.

• get_aria_accessibility_tree

  Returns the ARIA accessibility tree (YAML) for a frame snapshot in the trace. Reduces DOM token cost by ~90% vs raw HTML. Use action_index to target a specific action — defaults to the failed action, or the last snapshot if no failure.

• get_causal_chain_for_failure

  Walks backwards from the failed action and builds a chronological chain of preceding actions, network errors, and console errors. Surfaces the most likely root cause.

• get_console_errors

  Returns JS exceptions and warnings. Use limit/offset to page through results.

• get_dom_mutation_delta

  Diffs the ARIA tree before and after a specific action. Returns added and removed elements so the agent sees exactly what changed without comparing two full DOM dumps.

• get_element_state_at_failure

  Returns DOM attributes of the failing element at the moment of failure

• get_filtered_network_logs

  Returns only 4xx/5xx network responses, stripping static assets. Use limit/offset to page through results.

• get_screenshot_at_failure

  Returns the screenshot (base64 JPEG) from the trace closest to the moment of failure. Use when get_aria_accessibility_tree returns an empty or unhelpful tree — the image shows exactly what was on screen. Pass screenshot_index to retrieve any specific screenshot from the trace (0-based); omit to get the one nearest to the failure.

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Last commit

Oct 14, 2026 (14 days ago)

Last release

May 19, 2026 (5 months ago)

From GitHub (fetched Oct 24, 2026).

Details

Registry name

io.github.vola-trebla/playwright-trace-decoder-mcp

Version

0.2.3

Auth

No auth

Packages

npm playwright-trace-decoder-mcp

License

MIT

Repository

github.com/vola-trebla/playwright-trace-decoder-mcp

First seen

Oct 24, 2026

Last checked

Oct 24, 2026

Source

Official MCP Registrygithub-graphql