mcp-cli

mcp-cli

A single-binary MCP client for the shell. It calls one tool on one MCP server and prints the bare payload — no envelope, no session juggling, no hand-built JSON-RPC.

Servers are not configured twice: mcp reads the same configuration Claude Code uses, so anything in claude mcp list is callable from a script.

echo '{"libraryName": "Go"}' | mcp context7 resolve-library-id > result.json
jq -r '.libraries[0].id' result.json

Handy for shell pipelines, cron jobs, CI steps — and for AI agents, which can feed a jq projection of a large result into their context instead of the whole thing.

Install

go install github.com/tkukushkin/mcp-cli@latest

Or grab a prebuilt binary for darwin, linux or windows on amd64/arm64 from the releases page.

Usage

mcp-cli [-v] <server> <tool>
mcp-cli --version

• <server> — the name as it appears in claude mcp list.
• <tool> — the bare tool name, without the mcp__<server>__ prefix.
• Arguments are a JSON object on stdin. For a tool that takes none, use < /dev/null — or just run it interactively, since a TTY stdin also means {}.
• stdout is the tool's payload, not the MCP envelope: structuredContent as compact JSON when the server provides it, otherwise the text content as-is (which may itself be JSON — pipe it to jq as needed).
• Exit code is 0 on success, 1 on failure, with the error text on stderr (server not found, connection failure, or the tool's own error message).

Configuration

No config file of its own. Servers are looked up by name, first match wins:

1. ./.mcp.json — mcpServers (project scope)
2. ~/.claude.json — projects["$PWD"].mcpServers (local scope)
3. ~/.claude.json — mcpServers (user scope)

Servers authenticated through claude mcp login (OAuth) are not supported yet.

Scope

tools/call only, deliberately. Discovery (tools/list, resources, prompts) is what an MCP host is for; this is the escape hatch for when you're not in one.

License

MIT