mcp-cli

name	mcp-cli
description	Use when you need a one-off MCP server capability during research or debugging without permanently mounting it as a context-polluting integration.
allowed-tools	Read Bash
user-invocable	false

MCP CLI (Transient MCP Access)

Overview

The mcp CLI (from github.com/f/mcptools) discovers and invokes MCP server capabilities on-demand, then releases them. Use it when a task needs ONE server's tool — a doc fetch, a single query, a quick lookup — instead of permanently mounting that server as an always-loaded integration.

This keeps accelerators transient: spun up for the task, used, and dropped. A permanently mounted MCP server costs context on every session whether you call it or not. The CLI costs nothing until you run it. This is the same context-hygiene principle behind disabling unused MCP servers in monthly /mcp review.

Composes with cc10x:research (transient retrieval, used then released, never resident).

Prerequisite (install once)

Check first: command -v mcp. If absent, install:

git clone https://github.com/f/mcptools /tmp/mcptools
CGO_ENABLED=0 go build -o ~/.local/bin/mcp /tmp/mcptools/cmd/mcptools
# ensure ~/.local/bin is on PATH

If go is unavailable, report that the accelerator is missing and proceed with built-in tools — do NOT treat the missing binary as a task blocker (it is a fallback message, not a wall).

Flow: discover → call → release

1. Discover first — always. Never call a tool whose schema you have not seen.

mcp tools <server-command>                 # list tools
mcp tools --format json <server-command>   # full param schema for parsing
mcp resources <server-command>             # list resources
mcp prompts <server-command>               # list prompts

2. Lead read-only when exploring. Restrict the surface before you touch an unfamiliar server:

mcp guard --allow 'tools:read_*,list_*' --deny 'tools:write_*,delete_*' <server-command>

Drop the guard only once you know exactly which write you intend.

3. Call with params matching the discovered signature exactly (param:str, param:num, [optional]):

mcp call <tool_name> --params '<json>' -f json <server-command>

Output -f json for parsing, -f pretty for reading. Check exit code and stderr on failure — a non-zero exit is a real error, not a fallback message.

Server-command examples:

• stdio: npx -y @modelcontextprotocol/server-filesystem /path
• HTTP: pass the URL (auto-detected); SSE via --transport sse
• auth: --auth-header "Bearer <token>", --auth-user user:pass, or -e ENV_VAR for docker servers

Aliases (only for repeated use in one task)

If you call the same server several times, alias it; remove it when the task ends so nothing lingers:

mcp alias add <name> <server-command>   # then: mcp tools <name>, mcp call ... <name>
mcp alias remove <name>                 # release when done

Aliases persist in ~/.mcpt/aliases.json. Cleaning them up is part of keeping the accelerator transient.

Discipline

• Discover before calling; match param signatures exactly.
• Use JSON output when a downstream step parses the result.
• Guard to read-only while exploring; widen only with intent.
• Release aliases when the task is done — do not leave a transient tool resident.