DEV Community: Danny

Testing MCP Servers Used to Be a Pain. Here is How to Test Them with Zero Configuration.

Danny — Mon, 10 Aug 2026 00:54:40 +0000

When building Model Context Protocol (MCP) servers or AI agents that consume them, traditional API testing tools fall short. An MCP server isn't just a basic REST endpoint—it's a dynamic interface exposed to non-deterministic LLMs through stdio, HTTP, or SSE transports.

Testing tool schemas, transient network failures, and agent behaviors usually requires writing a mountain of boilerplate.

I built bubblemcp-test-kit to eliminate that friction: no backend accounts, no complex test setup, and zero instrumentation required.

What is bubblemcp-test-kit?
bubblemcp-test-kit is a lightweight, standalone testing toolkit designed specifically for MCP server developers and AI agent engineers.

Key features include:

Transport Agnostic: Work with stdio, HTTP, or SSE behind a unified API.

Fluent Assertions: Native matchers tailored for MCP response structures and JSON Schemas.

Mocking & Replay: Fabricate tool outputs locally or record real server runs to replay in offline CI environments.

Agent Trace & Fault Injection: Test if your AI agent calls tools in the right order and handles errors properly.

Quickstart Example
You can run a complete mock test suite without spinning up a live server:

import {
  createMockMcpClient,
  expectMcp,
  validateAgainstSchema,
  withRecording,
  createReplayClient,
} from 'bubblemcp-test-kit'

// 1. Define your tool contract
const healthCheckTool = {
  name: 'health_check',
  description: 'Reports service health',
  inputSchema: {
    type: 'object',
    properties: { service: { type: 'string' } },
    required: ['service'],
  },
  outputSchema: {
    type: 'object',
    properties: {
      service: { type: 'string' },
      status: { type: 'string', enum: ['ok', 'degraded', 'down'] },
      latencyMs: { type: 'number' },
    },
    required: ['service', 'status', 'latencyMs'],
  },
}

// 2. Set up a mock MCP client
const mock = createMockMcpClient({ tools: [healthCheckTool] })
mock.mockTool('health_check').resolves({ service: 'weather', status: 'ok', latencyMs: 12 })
mock.mockTool('flaky_tool').rejects('rate limited')

// 3. Chain fluent assertions
const result = await mock.callTool('health_check', { service: 'weather' })

expectMcp(result)
  .toBeValidMcpResponse()
  .not.toBeError()
  .toContainText('weather')
  .toMatchOutputSchema(healthCheckTool)

// 4. Validate schema violations locally
const badPayload = { service: 'weather', status: 'invalid-status', latencyMs: 'slow' }
const validation = validateAgainstSchema(badPayload, healthCheckTool.outputSchema)
console.log('Schema valid?', validation.valid) // false

// 5. Record & Replay for CI
const FIXTURE = './fixtures/health-check.json'
const recording = withRecording(mock, FIXTURE)
await recording.callTool('health_check', { service: 'weather' })

// Replay offline inside CI pipelines
const replay = await createReplayClient(FIXTURE)
const replayed = await replay.callTool('health_check', { service: 'weather' })
expectMcp(replayed).toBeValidMcpResponse()

Instant CLI Smoke Testing
If you just want to run an instant health check on an existing MCP server, use the CLI directly:

npx bubblemcp-test-kit test --url http://localhost:3000/mcp --security

It discovers your tools, validates outputs against declared JSON Schemas, scans for prompt poisoning or credential leaks, and outputs a formatted pass/fail report.

Check out the full repository and let me know what you think in the comments!

https://www.npmjs.com/package/bubblemcp-test-kit

https://github.com/BubbleMCP/bubblemcp-test-kit

Stop Writing Boilerplate for MCP Servers — Focus on Building AI Tools Instead

Danny — Tue, 14 Jul 2026 06:50:57 +0000

If you've started experimenting with the Model Context Protocol (MCP), you've probably discovered that building the tool itself is only half of the work.

Between deployment, authentication, configuration, monitoring, and updates, there's a surprising amount of infrastructure that has nothing to do with your actual idea.

After building several MCP projects, I kept asking myself:

Why isn't there a platform that makes deploying an MCP server as easy as deploying a web application?

That question eventually led me to build BubbleMCP.

👉 https://www.bubblemcp.com

The Problem

Most tutorials teach you how to create an MCP server.

Very few explain how to:

Deploy it reliably
Manage multiple servers
Share it with your team
Handle configuration
Scale as usage grows
Monitor health and availability
Keep deployments simple

Developers end up spending more time on infrastructure than on building useful AI tools.

What BubbleMCP Tries to Solve

BubbleMCP is designed to simplify the operational side of MCP development.

The goal is simple:

Spend your time building MCP tools—not managing servers.

The platform is focused on making it easier to:

🚀 Deploy MCP servers
⚙️ Manage configurations
🔄 Update deployments
📊 Monitor server status
🔒 Build with security in mind
📦 Organize multiple MCP projects

Instead of piecing together deployment scripts and infrastructure, you can focus on building the capabilities that matter.

Why This Matters

The AI ecosystem is evolving quickly.

Just as GitHub became the standard place to host code and Vercel simplified frontend deployment, I believe MCP developers will benefit from platforms purpose-built for hosting and managing MCP servers.

The goal isn't to replace your existing workflow—it's to reduce the friction between writing code and making it available.

Roadmap

I'm actively working on features including:

One-click deployments
Version management
Authentication improvements
Better developer experience
Monitoring dashboards
Project templates
Team collaboration
More integrations

Community feedback is helping shape what comes next.

I'd Love Your Feedback

BubbleMCP is still evolving, and I'd really appreciate input from developers building with MCP.

Questions I'm especially interested in:

What is the biggest pain point when deploying MCP servers?
What features would save you the most time?
What integrations would you like to see first?

You can explore the project here:

👉 https://www.bubblemcp.com

I'm always happy to discuss ideas, hear feature requests, or learn how you're using MCP in your own projects.

AI #OpenAI #Claude #MCP #ModelContextProtocol #DeveloperTools #TypeScript #NextJS #WebDevelopment #LLM #MachineLearning

I am building a wrapper tool for various API backend system to MCP server in a week.

Danny — Sun, 05 Jul 2026 04:57:13 +0000

But I am looking for a good tool to debugging the MCP and team collobration. Anyone can introduce one ?

Algorithms Challenge (2) Combination Coin Change - Different coins added up to a given amount

Danny — Mon, 19 Sep 2022 01:29:22 +0000

Question :
There are {1, 2 , 5} dollar types coins for selection. Use different combinations of these types coins to adding up to the given amount 50.

Answer:
We can use different types of dynamic programming methods to solve this problem. In this article , we choose to use Dynamic programming - Bottom up method.

The implementation logic is simple like this :

Set combinations as an array , its size is "amount +1"
combinations[0] = 1 , it means the first combination ways number is 1
We can loop the coins into the combinations array. When the amount(the value in the position of the combinations array) is greater than coin , then we can use the formular : combinations[amount] += combinations[amount - coin];

Code:



public class coinsCombinationWays {

    static int getTotalWays(int[] coins, int amount){
         int[] combinations = new int[amount + 1];
         combinations[0] = 1;

         for(int coin: coins) {
            for(int j=1; j<combinations.length; j++){
              if(j>=coin)
               combinations[j] += combinations[j-coin];
           }
         }
        return combinations[amount];
   } 

   public static void main(String[] args) {
       int[] coins = {1, 2, 5};
       int amount= 50; 

       int totalWays += getTotalWays(coins, amount);
       System.out.println(totalWays);
    }

}

Algorithms Challenge (1) How to print out Fibonacci series in two lines code

Danny — Fri, 16 Sep 2022 20:26:00 +0000

Print out Fibonacci numbers in range 0 - 100

Concept : print out two numbers every time

Code in java:

public class fibonacci {
   public static void main(String[] args) {
         for(int a = 0, b=1; a < 100 ; a+=b, b+=a)
             System.out.println(a + "," + (b<100 ? b + ",": ""));
    }
}

Result :
0,1,
1,2,
3,5,
8,13,
21,34,
55,89,