MCP Client

Universal MCP Client

Connect to any MCP server with progressive disclosure - load tool schemas on-demand instead of dumping thousands of tokens into context upfront.

Skill Location

This skill is located at: .claude/skills/mcp-client/

Script path: .claude/skills/mcp-client/scripts/mcp_client.py

Configuration

The script looks for config in this order:

1. MCP_CONFIG_PATH env var (custom path)
2. references/mcp-config.json (this skill's config - recommended)
3. .mcp.json in project root
4. ~/.claude.json

Your config file: .claude/skills/mcp-client/references/mcp-config.json

Edit this file to add your API keys. The example file (example-mcp-config.json) is kept as a reference template.

Security note:

• Never commit real API keys. This repo uses a placeholder ${AY_PROPOSALS_API_KEY} for the AY Proposals server.
• Option 1 (recommended): Create a private config and point the script to it: export MCP_CONFIG_PATH=~/.claude/skills/mcp-client/references/mcp-config.local.json (same structure, with your real token). Keep that file out of git.
• Option 2: Export your key in the shell: export AY_PROPOSALS_API_KEY=... and ensure your runtime interpolates env vars. If not, use Option 1.

If the user hasn't provided their Zapier API key yet, ask them for it.

Running Commands

All commands use the script at .claude/skills/mcp-client/scripts/mcp_client.py:

# List configured servers
python .claude/skills/mcp-client/scripts/mcp_client.py servers

# List tools from a server
python .claude/skills/mcp-client/scripts/mcp_client.py tools <server_name>

# Call a tool
python .claude/skills/mcp-client/scripts/mcp_client.py call <server> <tool> '{"arg": "value"}'

Workflow

1. Check config exists - Run servers command. If error, create .mcp.json
2. List servers - See what MCP servers are configured
3. List tools - Get tool schemas from a specific server
4. Call tool - Execute a tool with arguments

Commands Reference

Example: Zapier

# 1. List servers to confirm Zapier is configured
python .claude/skills/mcp-client/scripts/mcp_client.py servers

# 2. List Zapier tools
python .claude/skills/mcp-client/scripts/mcp_client.py tools zapier

# 3. Call a Zapier tool
python .claude/skills/mcp-client/scripts/mcp_client.py call zapier <tool_name> '{"param": "value"}'

Example: Sequential Thinking

# 1. List tools
python .claude/skills/mcp-client/scripts/mcp_client.py tools sequential-thinking

# 2. Use sequential thinking
python .claude/skills/mcp-client/scripts/mcp_client.py call sequential-thinking sequentialthinking '{"thought": "Breaking down the problem...", "thoughtNumber": 1, "totalThoughts": 5, "nextThoughtNeeded": true}'

Config Format

Config file format (references/mcp-config.json):

{
  "mcpServers": {
    "zapier": {
      "url": "https://mcp.zapier.com/api/v1/connect",
      "api_key": "your-api-key"
    },
    "sequential-thinking": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-sequential-thinking"]
    }
  }
}

Transport detection:

• url + api_key → FastMCP with Bearer auth (Zapier)
• command + args → stdio (local servers like sequential-thinking)
• url ending in /sse → SSE transport
• url ending in /mcp → Streamable HTTP

Error Handling

Errors return JSON:

{"error": "message", "type": "configuration|validation|connection"}

• configuration - Config file not found. Create .mcp.json
• validation - Invalid server or tool name
• connection - Failed to connect to server

Dependencies

pip install mcp fastmcp

References

• references/example-mcp-config.json - Template config file
• references/mcp-servers.md - Common server configurations
• references/python-mcp-sdk.md - Python SDK documentation