nxs

A pipe-friendly CLI that sends conversations to the Anthropic Messages API with MCP server passthrough.

nxs works in two modes: an interactive chat TUI for multi-turn conversations, and a pipe mode that reads from stdin for scripting and automation. MCP servers are passed directly to the API — no local MCP client needed.

Requirements

• Go 1.21+
• An Anthropic API key

Install

go install github.com/ironystock/nxs/cmd/nxs@latest

Or build from source:

git clone https://github.com/ironystock/nxs.git
cd nxs
go build -o bin/nxs cmd/nxs/main.go

Setup

Set your API key as an environment variable:

export ANTHROPIC_API_KEY="sk-ant-..."

Usage

Interactive chat

nxs

Launches a chat TUI. Type messages and press Enter to send. Shift+Enter for newlines. Ctrl+C or Esc to quit.

Pipe mode

echo "explain this error" | nxs

Reads stdin, sends it to the API, and prints the response to stdout.

Combine stdin with a query:

cat main.go | nxs "find bugs in this code"

git diff | nxs "write a commit message for this diff"

Output raw JSON instead of text:

echo "hello" | nxs --json

Flags

Flag	Description
--model	Override the model (default: claude-sonnet-4-5-20250514)
--json	Print full API response as JSON (pipe mode only)
--profile	Config profile (not yet implemented)

How MCP works in nxs

nxs passes MCP server configurations directly to the Anthropic Messages API using the mcp_servers field. The API connects to MCP servers and executes tools server-side. When the API responds with tool use blocks, nxs automatically handles the multi-turn loop until the final response is ready.

License

MIT