buzz-mcp-bridge

Give Buzz managed agents the MCP servers your Claude Desktop / Claude Code config already has, behind an explicit per-agent allowlist.

The problem

Buzz managed agents run as embedded engines: buzz-acp spawns the runtime (Claude, Goose, Codex) in ACP mode with host-controlled configuration. Your interactive MCP config, the servers you added in Claude Desktop or with claude mcp add -s user, does not inherit. That is deliberate and correct: your user config is your credentialed keyring (billing, admin consoles, your browser), and thirteen semi-trusted agents should not wake up holding it.

The hook Buzz gives you is mcp_command: one command per agent that speaks stdio MCP. This bridge is that command.

Related MCP server: harness_to_mcp

What it does

1. Reads mcpServers from Claude Code user scope (~/.claude.json) and Claude Desktop (claude_desktop_config.json). Code wins name collisions.

2. Connects only to the servers you explicitly allow for this agent.

3. Re-exposes their tools as one stdio MCP server, namespaced <server>__<tool>, the same naming Claude Code uses natively.

No allowlist, no startup. Grants are per agent, on purpose.

Install

git clone https://github.com/hachiflow/buzz-mcp-bridge
cd buzz-mcp-bridge && npm install

Write a tiny wrapper per agent (keeps secrets and allowlists out of Buzz's config file):

#!/bin/sh
# my-agent-mcp.sh
exec node /path/to/buzz-mcp-bridge/index.mjs --allow blotato,grafana

Point the agent's mcp_command at the wrapper. Today that field has no UI; edit managed-agents.json in Buzz Desktop's application-support directory:

~/Library/Application Support/xyz.block.buzz.app/agents/managed-agents.json
  -> your agent's entry -> "mcp_command": "/path/to/my-agent-mcp.sh"

The trap that will eat your evening: Buzz Desktop reads its config at app startup and spawns agents from memory. Restarting the agent is not enough. The order is: quit Buzz Desktop fully, edit the file, relaunch. Then verify from outside, never from inside the agent:

ps eww <agent-harness-pid> | tr ' ' '\n' | grep -c YOUR_EXPECTED_VAR

v0.1 limits (deliberate)

• stdio and streamable-http upstreams with static headers. Interactive OAuth flows are out of scope; use API-key headers for remote servers.

• Tool lists snapshot at startup. Tools only (no resources/prompts yet).

• ${VAR} expansion in header values reads the bridge's environment, so secrets can live in files your wrapper sources rather than in any config.

Why we built it

Hachiflow runs its marketing as a Buzz agent (Gary V) in our own hosted hive. He posts to X through Blotato's MCP, granted through exactly this bridge, and nothing else from our keyring. Field notes: https://hachiflow.com/blog

Apache-2.0. Not affiliated with Block; Buzz is their open-source project.