Agent skill
mcp-tester
Test MCP server connectivity and tool execution. Use when adding new MCP servers, debugging tool integration, or verifying tool availability. Supports stdio, http, and sse server types.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/testing/mcp-tester-rwxproject-agent-framework-7e6da20f
SKILL.md
MCP Server Testing
Test and debug MCP (Model Context Protocol) server connections.
Server Types
| Type | Transport | Use Case |
|---|---|---|
stdio |
Standard I/O | Local processes, CLI tools |
http |
HTTP/HTTPS | Remote APIs, cloud services |
sse |
Server-Sent Events | Streaming endpoints |
Test Categories
1. Connection Test
Verify server is reachable and initializes correctly.
# Test stdio server
npx -y @modelcontextprotocol/inspector stdio -- npx -y @modelcontextprotocol/server-filesystem /tmp
# Test HTTP server
curl -X POST https://mcp.service.com/initialize \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","method":"initialize","params":{},"id":1}'
2. Tool Discovery
List available tools from a connected server.
# Using MCP inspector
npx -y @modelcontextprotocol/inspector stdio -- python ./mcp_servers/my_server.py
# Check tool listing
curl -X POST https://mcp.service.com/tools/list \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","method":"tools/list","params":{},"id":2}'
3. Tool Execution
Test individual tool invocation.
# Python test script
import asyncio
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client
async def test_tool():
server_params = StdioServerParameters(
command="npx",
args=["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
)
async with stdio_client(server_params) as (read, write):
async with ClientSession(read, write) as session:
await session.initialize()
# List tools
tools = await session.list_tools()
print(f"Available tools: {[t.name for t in tools.tools]}")
# Execute tool
result = await session.call_tool(
"read_file",
{"path": "/tmp/test.txt"}
)
print(f"Result: {result.content}")
asyncio.run(test_tool())
4. Error Handling
Verify graceful error handling.
# Test invalid tool call
try:
result = await session.call_tool("nonexistent_tool", {})
except Exception as e:
print(f"Expected error: {e}")
# Test invalid parameters
try:
result = await session.call_tool("read_file", {"invalid": "param"})
except Exception as e:
print(f"Expected error: {e}")
Configuration Validation
.mcp.json Schema
{
"mcpServers": {
"server-name": {
"type": "stdio | http | sse",
"command": "string (for stdio)",
"args": ["array", "of", "args"],
"env": {
"VAR": "value or ${ENV_VAR}"
},
"url": "string (for http/sse)",
"headers": {
"Authorization": "Bearer ${TOKEN}"
}
}
}
}
Environment Variable Expansion
{
"env": {
"API_KEY": "${MY_API_KEY}",
"BASE_URL": "${BASE_URL:-http://localhost:8080}"
}
}
Debugging Commands
# Check if server process starts
npx -y @modelcontextprotocol/server-filesystem /tmp
# Verbose mode for debugging
DEBUG=mcp:* npx -y @modelcontextprotocol/inspector stdio -- ./my_server
# Check environment variables
env | grep -E 'API_KEY|TOKEN|URL'
# Test HTTP endpoint
curl -v https://mcp.service.com/health
Common Issues
| Issue | Cause | Solution |
|---|---|---|
| Connection refused | Server not running | Start server process |
| Tool not found | Wrong tool name | Check tools/list response |
| Auth error | Missing/invalid token | Set environment variable |
| Timeout | Server slow/hanging | Check server logs |
| Parse error | Invalid JSON-RPC | Validate request format |
Health Check Endpoint
@app.get("/health")
async def health_check():
"""MCP server health check."""
return {"status": "healthy", "version": "1.0.0"}
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