Bloomberg MCP Gateway

Production-grade MCP gateway that gives a Linux-hosted agent (Hermes) controlled access to the Bloomberg Desktop API (blpapi) on a Windows Bloomberg Terminal workstation, over a private Tailscale network.

• Protocol: stateless MCP Streamable HTTP, revision 2026-07-28

• Transport: HTTPS via Tailscale Serve -> http://127.0.0.1:8765

• Bloomberg: Desktop API only, local 127.0.0.1:8194 (BBComm never exposed)

• Auth: private static bearer tokens mapped to server-owned principals

• Safety: policy, cost/quota budgets, principal-bound handles, audit trail, entitlement circuit breaker, bounded result storage

• CI: deterministic fake backend allows development and testing without a Bloomberg Terminal

See SPEC.md for the full design specification.

Layout

src/bloomberg_mcp/   gateway implementation (native blpapi confined to blp/)
config/              default configuration and policy examples
scripts/             PowerShell deployment and operations scripts
tests/               unit, property and contract tests (fake backend)
docs/                architecture, deployment, security and operations docs

Related MCP server: Bloomberg MCP

Development setup (Windows)

Requires Python 3.12 and uv. All work happens in a project-local virtual environment (.venv); global Python environments are never touched.

# 1. Create the isolated virtual environment
uv venv

# 2. Install the gateway with dev tooling (blpapi is fetched from the
#    Bloomberg package index automatically, see pyproject.toml)
uv sync --extra dev

# 3. Run the test suite against the deterministic fake backend
uv run pytest

# 4. Lint and type-check
uv run ruff check src tests
uv run mypy

Without uv, the equivalent plain-Python flow is:

python -m venv .venv
.venv\Scripts\python -m pip install -e ".[dev]" `
  --extra-index-url https://blpapi.bloomberg.com/repository/releases/python/simple/

Running the gateway

# Fake backend (no Bloomberg Terminal required)
uv run bloomberg-mcp --backend fake

# Native backend (Bloomberg Terminal must be running and logged on)
uv run bloomberg-mcp --config config/default.yaml --policy config/policy.example.yaml

The gateway binds 127.0.0.1:8765 by default and refuses to start twice (Windows named mutex). Configure Tailscale Serve separately (scripts/configure-tailscale.ps1) to terminate tailnet-only HTTPS.

Milestone status

Bloomberg-side verification items (Terminal connectivity, entitlements, operation limits) require an actual logged-on Terminal; see docs/deployment.md and scripts/environment-probe.ps1.

Security notes

• Never expose port 8765 or BBComm port 8194 beyond localhost.

• Bearer tokens must have >= 256 bits of entropy; rotate with a bounded overlap.

• Policy limits do not replace Bloomberg contractual or entitlement limits.