MCP CLI: On-Demand MCP Server Usage

Use the mcp CLI tool to dynamically discover and invoke MCP server capabilities without pre-configuring them as permanent integrations.

When to Use This Skill

Use this skill when you need to:

• Explore an MCP server's capabilities before deciding to use it
• Make one-off calls to an MCP server without permanent integration
• Access MCP functionality without polluting the context window
• Test or debug MCP servers
• Use MCP servers that aren't pre-configured

Prerequisites

The mcp CLI must be installed at ~/.local/bin/mcp. If not present:

# Clone and build
cd /tmp && git clone --depth 1 https://github.com/f/mcptools.git
cd mcptools && CGO_ENABLED=0 go build -o ~/.local/bin/mcp ./cmd/mcptools

Always ensure PATH includes the binary:

export PATH="$HOME/.local/bin:$PATH"

Discovery Workflow

Step 1: Discover Available Tools

mcp tools <server-command>

Examples:

# Filesystem server
mcp tools npx -y @modelcontextprotocol/server-filesystem /path/to/allow

# Memory/knowledge graph server
mcp tools npx -y @modelcontextprotocol/server-memory

# GitHub server (requires token)
mcp tools docker run -i --rm -e GITHUB_PERSONAL_ACCESS_TOKEN ghcr.io/github/github-mcp-server

# HTTP-based server
mcp tools https://example.com/mcp

Step 2: Discover Resources (if supported)

mcp resources <server-command>

Resources are data sources the server exposes (files, database entries, etc.).

Step 3: Discover Prompts (if supported)

mcp prompts <server-command>

Prompts are pre-defined prompt templates the server provides.

Step 4: Get Detailed Info (JSON format)

# For full schema details including parameter types
mcp tools --format json <server-command>
mcp tools --format pretty <server-command>

Making Tool Calls

Basic Syntax

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

Examples

Read a file:

mcp call read_file --params '{"path": "/tmp/example.txt"}' \
  npx -y @modelcontextprotocol/server-filesystem /tmp

Write a file:

mcp call write_file --params '{"path": "/tmp/test.txt", "content": "Hello world"}' \
  npx -y @modelcontextprotocol/server-filesystem /tmp

List directory:

mcp call list_directory --params '{"path": "/tmp"}' \
  npx -y @modelcontextprotocol/server-filesystem /tmp

Create entities (memory server):

mcp call create_entities --params '{"entities": [{"name": "Project", "entityType": "Software", "observations": ["Uses TypeScript"]}]}' \
  npx -y @modelcontextprotocol/server-memory

Search (memory server):

mcp call search_nodes --params '{"query": "TypeScript"}' \
  npx -y @modelcontextprotocol/server-memory

Complex Parameters

For nested objects and arrays, ensure valid JSON:

mcp call edit_file --params '{
  "path": "/tmp/file.txt",
  "edits": [
    {"oldText": "foo", "newText": "bar"},
    {"oldText": "baz", "newText": "qux"}
  ]
}' npx -y @modelcontextprotocol/server-filesystem /tmp

Output Formats

# Table (default, human-readable)
mcp call <tool> --params '{}' <server>

# JSON (for parsing)
mcp call <tool> --params '{}' -f json <server>

# Pretty JSON (readable JSON)
mcp call <tool> --params '{}' -f pretty <server>

Reading Resources

# List available resources
mcp resources <server-command>

# Read a specific resource
mcp read-resource <resource-uri> <server-command>

# Alternative syntax
mcp call resource:<resource-uri> <server-command>

Using Prompts

# List available prompts
mcp prompts <server-command>

# Get a prompt (may require arguments)
mcp get-prompt <prompt-name> <server-command>

# With parameters
mcp get-prompt <prompt-name> --params '{"arg": "value"}' <server-command>

Server Aliases (for repeated use)

If using a server frequently during a session:

# Create alias

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