bridge-probe-mcp

[bridge-probe-mcp] This project was developed and is maintained by AI. Use at your own discretion.

A one-tool diagnostic MCP, not a fleet product. It exists to answer one question for mcp-host issue #732: does a ~5 MB single-shot response survive the hosted browser-bridge path intact — extension → WAN → Cloudflare → the BridgeRoom Durable Object → the runner agent → this child — and how long does it take?

What it does

One tool, probe_5mib_body, no arguments. It fetches a fixed, pure-ASCII 5,242,880-byte (5 MiB) text file committed to this repo (assets/payload-5mib.txt) from raw.githubusercontent.com, through the browser bridge, and reports:

{
  "requestedBytes": 5242880,
  "receivedBytes": 5242880,
  "elapsedMs": 1234,
  "truncated": false,
  "upstreamStatus": 200,
  "url": "https://raw.githubusercontent.com/..."
}

The payload is deliberately plain ASCII, not random bytes: the bridge's request() verb decodes every response body as a UTF-8 string, which is lossy for arbitrary binary (a httpbin.org/bytes/{n}-style source would have its invalid byte sequences replaced with U+FFFD, inflating the re-encoded length unpredictably). ASCII round-trips through UTF-8 losslessly, so receivedBytes is the exact byte count that crossed the whole path — a real number to design against, not an approximation.

Related MCP server: MCP Server Streamable

Deliberately NOT a fleet product

No npm publish, no MCP registry listing, no ClawHub, no release-please, no branch rulesets, no ceremony beyond build + test. It is meant to be registered once on mcp-host via --github, paired to a browser, called a few times to get a measurement, and then left running or torn down — see mcp-host's docs/plans/2026-09-11-single-tier-autoscale-and-backlog.md decision 7 and issue #732 for the context.

Hosting

mcp-host register --slug bridge-probe --github chrischall/bridge-probe-mcp --data-dir
mcp-host list   # grab the reg_… id
curl -X PUT "$MCP_HOST_URL/api/v1/registrations/<reg_id>" \
  -H "authorization: Bearer $MCP_HOST_ADMIN_TOKEN" -H 'content-type: application/json' \
  -d '{"bridge":true,"bridgePortEnv":"BRIDGE_PROBE_WS_PORT"}'
mcp-host bridge new "diagnostic browser"

Then approve the pair code in the Transporter extension popup once, and call probe_5mib_body through the connector.