[Bug] MCP tools fail with -32603 when JWT_SECRET is set (cross-host MCP)

[ArtemSultanov-PG]

Environment

• BrowserOS Version: 0.46.25.0
• Chromium Version: 148.0.7966.97
• Architecture: macOS (Intel)
• OS: macOS 14.5+

Problem

When AGENT_RUNNER_JWT_SECRET is set, the MCP server returns HTTP 500 / JSON-RPC error -32603 Internal Server Error on all tool calls.

Setup (Cross-host MCP)

• Agent: 192.168.88.61 (GPU server)
• BrowserOS: 192.168.88.58 (MacBook Pro)
• CDP port: 9015 (localhost)

Connection:

1. JWT set via launchctl setenv
2. SSH tunnel: ssh -L 19015:127.0.0.1:9015 -N -f macbook
3. MCP connects to port 9007 via Streamable HTTP
4. CDP via tunnel on 19015

Logs:

{"level":30,"msg":"Connected to CDP on port 9015"}
{"level":50,"msg":"Unhandled Error" at handlePostRequest}

Expected

• initialize returns 200 with serverInfo
• tools/list returns 16 tools
• tools/call returns snapshot

Actual

• All calls return 500 with -32603 Internal server error

Questions

1. Is Streamable HTTP correct for cross-host MCP?
2. Should JWT be set via plist EnvironmentVariables?
3. Known issues with handlePostRequest?

Full details: /home/pg/pgwiki/browseros_issue.md

[shadowfax92]

Thanks this should be fixed in newer versions!