playwright-trace-decoder-mcp
Server Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Features and capabilities supported by this server
Protocol revision2025-11-25
| Capability | Details |
|---|---|
| tools | {
"listChanged": true
} |
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| get_test_metadataA | Returns test metadata: title, browser, platform, viewport, and start time |
| get_trace_summaryB | Returns the failing action and top-level error message from a Playwright trace |
| get_action_timelineA | Returns a paginated timeline of all actions with locators and timings. Use limit/offset to page through large traces. |
| get_filtered_network_logsA | Returns only 4xx/5xx network responses, stripping static assets. Use limit/offset to page through results. |
| get_console_errorsB | Returns JS exceptions and warnings. Use limit/offset to page through results. |
| get_aria_accessibility_treeA | 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_element_state_at_failureB | Returns DOM attributes of the failing element at the moment of failure |
| analyze_race_conditionsA | 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. |
| get_dom_mutation_deltaA | 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_causal_chain_for_failureA | 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. |
| generate_error_signatureA | 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. |
| compare_tracesA | 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. |
| get_screenshot_at_failureA | 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. |
| correlate_dom_and_networkA | 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?' |
| extract_trace_metadata_strictA | 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. |
| detect_performance_anomaliesA | 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. |
| map_locator_to_sourceA | Maps a failing browser interaction (or a specific action index) to its corresponding line of code in the test file using the execution stack from the test runner. |
| extract_critical_framesA | 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. |
| trim_trace_archiveA | Shrinks a Playwright trace zip file by deleting screenshots outside the critical failure window (t_fail - 5s to t_fail + 1s). Returns original vs trimmed size and path to the new archive (.trimmed.zip). |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
No prompts | |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
No resources | |
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