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:

bash

# 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:

bash

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

Discovery Workflow

Step 1: Discover Available Tools

bash

mcp tools <server-command>

Examples:

bash

# 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)

bash

mcp resources <server-command>

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

Step 3: Discover Prompts (if supported)

bash

mcp prompts <server-command>

Prompts are pre-defined prompt templates the server provides.

Step 4: Get Detailed Info (JSON format)

bash

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

Making Tool Calls

Basic Syntax

bash

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

Examples

Read a file:

bash

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

Write a file:

bash

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

List directory:

bash

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

Create entities (memory server):

bash

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

Search (memory server):

bash

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

Complex Parameters

For nested objects and arrays, ensure valid JSON:

bash

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

bash

# 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

bash

# 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

bash

# 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:

bash

# Create alias
mcp alias add fs npx -y @modelcontextprotocol/server-filesystem /home/user

# Use alias
mcp tools fs
mcp call read_file --params '{"path": "README.md"}' fs

# List aliases
mcp alias list

# Remove when done
mcp alias remove fs

Aliases are stored in

~/.mcpt/aliases.json

Authentication

HTTP Basic Auth

bash

mcp tools --auth-user "username:password" https://api.example.com/mcp

Bearer Token

bash

mcp tools --auth-header "Bearer your-token-here" https://api.example.com/mcp

Environment Variables (for Docker-based servers)

bash

mcp tools docker run -i --rm \
  -e GITHUB_PERSONAL_ACCESS_TOKEN="$GITHUB_TOKEN" \
  ghcr.io/github/github-mcp-server

Transport Types

Stdio (default for npx/node commands)

bash

mcp tools npx -y @modelcontextprotocol/server-filesystem /tmp

HTTP (auto-detected for http/https URLs)

bash

mcp tools https://example.com/mcp

SSE (Server-Sent Events)

bash

mcp tools http://localhost:3001/sse
# Or explicitly:
mcp tools --transport sse http://localhost:3001

Common MCP Servers

Filesystem

bash

# Allow access to specific directory
mcp tools npx -y @modelcontextprotocol/server-filesystem /path/to/allow

Memory (Knowledge Graph)

bash

mcp tools npx -y @modelcontextprotocol/server-memory

GitHub

bash

export GITHUB_PERSONAL_ACCESS_TOKEN="your-token"
mcp tools docker run -i --rm -e GITHUB_PERSONAL_ACCESS_TOKEN ghcr.io/github/github-mcp-server

Brave Search

bash

export BRAVE_API_KEY="your-key"
mcp tools npx -y @anthropic/mcp-server-brave-search

Puppeteer (Browser Automation)

bash

mcp tools npx -y @anthropic/mcp-server-puppeteer

Best Practices

1. Always Discover First

Before calling tools, run

mcp tools

to understand what's available and the exact parameter schema.

2. Use JSON Format for Parsing

When you need to process results programmatically:

bash

mcp call <tool> --params '{}' -f json <server> | jq '.field'

3. Validate Parameters

The table output shows parameter signatures. Match them exactly:

```
param:str
```
= string
```
param:num
```
= number
```
param:bool
```
= boolean
```
param:str[]
```
= array of strings
```
[param:str]
```
= optional parameter

4. Handle Errors Gracefully

Tool calls may fail. Check exit codes and stderr:

bash

if ! result=$(mcp call tool --params '{}' server 2>&1); then
  echo "Error: $result"
fi

5. Use Aliases for Multi-Step Operations

If making several calls to the same server:

bash

mcp alias add tmp-server npx -y @modelcontextprotocol/server-filesystem /tmp
mcp call list_directory --params '{"path": "/tmp"}' tmp-server
mcp call read_file --params '{"path": "/tmp/file.txt"}' tmp-server
mcp alias remove tmp-server

6. Restrict Capabilities with Guard

For safety, limit what tools are accessible:

bash

# Only allow read operations
mcp guard --allow 'tools:read_*,list_*' --deny 'tools:write_*,delete_*' \
  npx -y @modelcontextprotocol/server-filesystem /home

Debugging

View Server Logs

bash

mcp tools --server-logs <server-command>

Check Alias Configuration

bash

cat ~/.mcpt/aliases.json

Verbose Output

Use

--format pretty

for detailed JSON output to debug parameter issues.

Quick Reference

Action	Command
List tools	`mcp tools <server>`
List resources	`mcp resources <server>`
List prompts	`mcp prompts <server>`
Call tool	`mcp call <tool> --params '<json>' <server>`
Read resource	`mcp read-resource <uri> <server>`
Get prompt	`mcp get-prompt <name> <server>`
Add alias	`mcp alias add <name> <server-command>`
Remove alias	`mcp alias remove <name>`
JSON output	Add `-f json` or `-f pretty`

Example: Complete Workflow

bash

# 1. Discover what's available
mcp tools npx -y @modelcontextprotocol/server-filesystem /home/user/project

# 2. Check for resources
mcp resources npx -y @modelcontextprotocol/server-filesystem /home/user/project

# 3. Create alias for convenience
mcp alias add proj npx -y @modelcontextprotocol/server-filesystem /home/user/project

# 4. Explore directory structure
mcp call directory_tree --params '{"path": "/home/user/project"}' proj

# 5. Read specific files
mcp call read_file --params '{"path": "/home/user/project/README.md"}' proj

# 6. Search for patterns
mcp call search_files --params '{"path": "/home/user/project", "pattern": "**/*.ts"}' proj

# 7. Clean up alias
mcp alias remove proj

Troubleshooting

"command not found: mcp"

Ensure PATH is set:

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

JSON parse errors

Escape special characters properly
Avoid shell expansion issues by using single quotes around JSON
For complex JSON, write to a temp file and use
```
--params "$(cat params.json)"
```

Server timeout

Some servers take time to start. The mcp CLI waits for initialization automatically.

Permission denied

For filesystem server, ensure the allowed directory path is correct and accessible.

mcp-cli

NPX Install

Tags

SKILL.md Content

MCP CLI: On-Demand MCP Server Usage

When to Use This Skill

Prerequisites

Discovery Workflow

Step 1: Discover Available Tools

Step 2: Discover Resources (if supported)

Step 3: Discover Prompts (if supported)

Step 4: Get Detailed Info (JSON format)

Making Tool Calls

Basic Syntax

Examples

Complex Parameters

Output Formats

Reading Resources

Using Prompts

Server Aliases (for repeated use)

Authentication

HTTP Basic Auth

Bearer Token

Environment Variables (for Docker-based servers)

Transport Types

Stdio (default for npx/node commands)

HTTP (auto-detected for http/https URLs)

SSE (Server-Sent Events)

Common MCP Servers

Filesystem

Memory (Knowledge Graph)

GitHub

Brave Search

Puppeteer (Browser Automation)

Best Practices

1. Always Discover First

2. Use JSON Format for Parsing

3. Validate Parameters

4. Handle Errors Gracefully

5. Use Aliases for Multi-Step Operations

6. Restrict Capabilities with Guard

Debugging

View Server Logs

Check Alias Configuration

Verbose Output

Quick Reference

Example: Complete Workflow

Troubleshooting

"command not found: mcp"

JSON parse errors

Server timeout

Permission denied