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.
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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
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.
bash
# 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.
bash
# 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
# 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.
python
# 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
json
{
"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 ${TOKEN}"
}
}
}
}
Environment Variable Expansion
json
{
"env": {
"API_KEY": "${MY_API_KEY}",
"BASE_URL": "${BASE_URL:-http://localhost:8080}"
}
}
Debugging Commands
bash
# 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
python
@app.get("/health")
async def health_check():
"""MCP server health check."""
return {"status": "healthy", "version": "1.0.0"}
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