Playwright MCP tools not available in GitHub Agentic Workflows (initialize: EOF during MCP init)

[Phonesis]

In GitHub Agentic Workflows, the Playwright MCP server appears connected/healthy, but no Playwright tools are registered for the agent. Calls such as browser_navigate fail because the tool list is empty.

What I expected:

Playwright MCP tools (for example browser_navigate) should register and be callable by the agent during workflow execution.

What happened:

Agent error: Tool 'browser_navigate' does not exist
MCP gateway logs show Playwright startup followed by registration failure:
Starting server name=playwright
Failed to register tools error="initialize: EOF" name=playwright
Gateway health/connection can still look green even though tool registration failed.

Environment
Platform: GitHub Actions hosted runner (Ubuntu)
Workflow system: GitHub Agentic Workflows (gh-aw) - https://github.com/githubnext/agentics/blob/main/docs/daily-accessibility-review.md
MCP server image: mcr.microsoft.com/playwright/mcp:latest
Date observed: 2026-02-16

Repro steps
Configure Playwright MCP in an Agentic Workflow.
Run the workflow in GitHub Actions.
Have the agent call a Playwright tool (for example browser_navigate).
Observe missing-tool error and initialize: EOF in logs.

Suspected cause
Playwright MCP initialization may attempt browser startup that is incompatible with GitHub Actions sandbox constraints (for example no-new-privileges / Chromium sandbox constraints), causing init pipe closure and EOF before tools register.

Notes
Removing --init from container args reduced startup instability but did not resolve initialize: EOF.
This looks like a tool-registration failure masked by a healthy connection status.

Request
Please confirm whether Playwright MCP is expected to work on standard GitHub-hosted runners, and if so, document required runtime flags/entrypoint changes (for example sandbox/headless constraints) to ensure successful tool registration.