Blowhorn

Blowhorn MCP server

Blowhorn is an AI-native social media manager. This repo holds the small launcher that starts Blowhorn's MCP server, and every marketplace listing file for it. The MCP server itself ships inside the Blowhorn desktop app and runs locally on your Mac over stdio, so its tools always match the Blowhorn you have installed.

• One tool per Blowhorn command, grouped Act, Manage, Connect, Run, Observe and Meta. From Blowhorn 1.62.0, risky tools are hidden by default because each removes or replaces your install, removes a background service or LaunchAgent, or signs you out: uninstall, service_uninstall, auth_logout, desktop_build and desktop_install, and after Blowhorn 1.84.0 also service_adopt and chrome_attach_chrome_uninstall_agent. To serve one, name it with --allow-hidden-tool (repeatable) or in BLOWHORN_MCP_ALLOW_HIDDEN_TOOLS; see Hidden tools.
• Dry run first: reads run as asked. Every state change runs as a dry run unless the call confirms it.
• Approval mode applies: when it is on, work an agent confirms waits for you to approve it in the Blowhorn app.
• No secrets: tool results never carry secrets, and tool arguments are never logged.

Reference: https://blowhorn.ai/docs/reference/mcp-server/

Requirements

• macOS.
• Blowhorn 1.61.0 or later, from https://blowhorn.ai/download/.
• Open Blowhorn once. On first run it writes ~/.local/bin/blowhorn-mcp, the command every MCP client below starts.

Install

Every client starts ~/.local/bin/blowhorn-mcp as a stdio server. Step by step for each client: https://blowhorn.ai/docs/how-to/set-up/connect-mcp-client/. What the server does: https://blowhorn.ai/docs/reference/mcp-server/.

Claude Code

claude mcp add blowhorn -- ~/.local/bin/blowhorn-mcp

Or install it as a Claude Code plugin from this repo, which also adds the Blowhorn skill:

/plugin marketplace add blowhorn-ai/blowhorn-mcp/plugin install blowhorn@blowhorn

Claude Desktop

In ~/Library/Application Support/Claude/claude_desktop_config.json, with your own user name in place of YOU (Claude Desktop does not expand ~):

{  "mcpServers": {    "blowhorn": {      "command": "/Users/YOU/.local/bin/blowhorn-mcp"    }  }}

Cursor

In ~/.cursor/mcp.json (Cursor interpolates ${userHome}):

{  "mcpServers": {    "blowhorn": {      "command": "${userHome}/.local/bin/blowhorn-mcp"    }  }}

This repo is also a Cursor plugin (.cursor-plugin/plugin.json and mcp.json), which adds the Blowhorn skill as well.

VS Code

In your workspace's .vscode/mcp.json:

{  "servers": {    "blowhorn": {      "type": "stdio",      "command": "${userHome}/.local/bin/blowhorn-mcp"    }  }}

Gemini CLI

gemini extensions install https://github.com/blowhorn-ai/blowhorn-mcp

The extension runs this repo's own launcher with node, which then starts ~/.local/bin/blowhorn-mcp. Gemini CLI fills in only ${extensionPath}, ${workspacePath} and ${/} in an extension manifest, never ${HOME}, so the extension cannot name ~/.local/bin/blowhorn-mcp directly; Gemini CLI itself runs on Node, so node is always there.

Cline

Follow llms-install.md. Cline does not expand ~, so it needs the absolute path /Users/<you>/.local/bin/blowhorn-mcp.

npm

The launcher is published on npm as blowhorn-mcp and in the official MCP Registry as io.github.blowhorn-ai/blowhorn, so any client can start the server with:

npx -y blowhorn-mcp

In a client's JSON config, that is "command": "npx" with "args": ["-y", "blowhorn-mcp"]; on Claude Code it is claude mcp add blowhorn -- npx -y blowhorn-mcp. The npm launcher needs Node.js 20 or later and the Blowhorn app installed, and any arguments after blowhorn-mcp go to the server unchanged.

Example prompts

All of these are reads or dry runs:

1. "List my Blowhorn profiles and tell me which ones need to sign in again."
2. "Show my analytics for the last week and name the post that did best."
3. "Draft a post announcing our 2.0 release for my LinkedIn and X profiles, add it to the queue as a dry run, and show me what would be queued."
4. "What is scheduled to go out today?"
5. "Check that Blowhorn's service is running and report any diagnostics."

How the launcher finds the server

bin/blowhorn-mcp.js (the npm launcher, and the Gemini extension's command) uses the first of these that is present:

1. ~/.local/bin/blowhorn-mcp, the launcher the Blowhorn app writes.
2. The engine the app recorded in ~/Library/Application Support/Blowhorn/engine.json.
3. /Applications/Blowhorn.app, then ~/Applications/Blowhorn.app.

Before it starts the server from 2 or 3, the launcher checks that the blowhorn command every tool call runs can be found: BLOWHORN_MCP_CLI if you set it, then ~/.local/bin/blowhorn, then blowhorn on your PATH. If none is there, it stops with blowhorn_setup_incomplete rather than start a server whose every tool call would fail.

The launcher writes nothing to stdout, which belongs to the MCP protocol. Its own messages go to stderr. blowhorn-mcp --launcher-version prints the launcher's version.

Troubleshooting

• code: blowhorn_missing: the Blowhorn app was not found. Install it from https://blowhorn.ai/download/, open it once, then restart your MCP client. An app kept outside /Applications and ~/Applications is found once it has been opened.
• code: blowhorn_mcp_server_missing: the app was found but has no MCP server inside it. Update or reinstall Blowhorn from https://blowhorn.ai/download/.
• code: blowhorn_setup_incomplete: the app was found but has not finished setting up, so the blowhorn command is not in ~/.local/bin yet. Open Blowhorn once, then restart your MCP client. To use a blowhorn command kept elsewhere, set BLOWHORN_MCP_CLI to its path in the server's env.
• Your client shows no server: check that ~/.local/bin/blowhorn-mcp exists and is executable (test -x ~/.local/bin/blowhorn-mcp && echo ok), that the client's config uses a path it can expand (see the client's section above), and check the client's MCP log, where the launcher's messages appear.

More help: https://blowhorn.ai/docs/reference/support/

Privacy Policy

Your data stays on your Mac, in the Blowhorn app. The MCP server runs locally and sends your data only to the social platforms and services you signed in to in Blowhorn. Tool results never carry secrets, and tool arguments are never logged.

• Privacy policy: https://blowhorn.ai/legal/privacy/
• Terms: https://blowhorn.ai/legal/terms/
• Support: https://blowhorn.ai/docs/reference/support/

Repository layout

Files marked generated are written by make generate from listing/listing.json and package.json. Never hand-edit them: change the source and regenerate. make check fails when they drift.

The hosted/ folder holds an interim read-only gateway; see hosted/README.md.

Development

make install   # dev tooling into tools/node_modules and hosted/node_modulesmake generate  # rewrite the generated filesmake check     # what CI runs: drift, schemas, copy rules, skill, docs facts, logo, tests, tarball, hosted/

npm test runs the same tests as make test; npm run check runs make check. The dev tooling lives in tools/ because the root package's "os": ["darwin"] makes npm refuse to install anything at the root on any other platform, and CI runs there too.

Maintainers

Releases, npm publishing and the MCP Registry: see MAINTAINERS.md.

The version in server.json, and in every plugin and extension manifest, is this npm launcher's version from package.json, not the Blowhorn desktop app's. Each MCP Registry publish pairs with an npm publish of the same version, and the launcher works with any Blowhorn 1.61.0 or later, so the app's version says nothing about what the registry entry installs.

License

Apache-2.0. See LICENSE.