MCP Sidecar runs on your own machine — the client starts it, so there is no endpoint to ping. 54 installs a week from npm. Last commit 2 Jun 2026.
Cross-platform MCP server for managing long-lived background processes from any MCP client
We read the source, 23 h ago · rules 3dff92dd89df
What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.
этот файл ставится пользователю, но в репозитории его нет
execFileSync(binPath, process.argv.slice(2), { stdio: "inherit" });
Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.
We found places where it runs commands, builds paths or queries from values it is given. None of that is a flaw by itself — it becomes one when the code changes, and code changes quietly between releases. We re-read it on every one.
This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.
claude mcp add mcp-sidecar -- npx -y mcp-sidecar
{
"mcpServers": {
"mcp-sidecar": {
"args": [
"-y",
"mcp-sidecar"
],
"command": "npx"
}
}
}
[mcp_servers.mcp-sidecar]
command = "npx"
args = ["-y", "mcp-sidecar"]
{
"mcpServers": {
"mcp-sidecar": {
"args": [
"-y",
"mcp-sidecar"
],
"command": "npx"
}
}
}
{
"mcpServers": {
"mcp-sidecar": {
"args": [
"-y",
"mcp-sidecar"
],
"command": "npx"
}
}
}
This one needs environment variables set before it will start:
SIDECAR_MAX_PROCESSES (Maximum number of concurrent managed processes (default: 10)), SIDECAR_BUFFER_SIZE (Output buffer size per stream in bytes (default: 1048576)), SIDECAR_KILL_TIMEOUT (Milliseconds to wait between graceful and forced termination (default: 5000)), SIDECAR_CLEANUP_AFTER (Seconds before exited processes are auto-removed. 0 disables cleanup (default: 1800)), SIDECAR_MAX_OUTPUT_SIZE (Global cap on bytes returned by the output tool. 0 means unlimited (default: 0)), SIDECAR_ALLOWED_EXECUTABLES (Comma-separated allowlist of executable names. When set, enables security mode with direct exec (no shell). Unset means security disabled.), SIDECAR_BLOCKED_PATTERNS (Comma-separated regex patterns to reject in commands. Only applies when security is enabled.), SIDECAR_AUDIT_LOG (Audit log destination. 'true' writes to cwd, 'temp' writes to OS temp dir, or a directory path. Unset disables audit logging.).
The author declared them in the registry entry; get the values from the project itself.
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Answers built from our own checks of this server.