apidays Munich 2025 - Let’s build, debug and test a magic MCP server in Postman with a few clicks, Johannes Nicolai (Postman)

Let’s build, debug and test a magic MCP server in Postman with a few clicks
Johannes Nicolai, Strategic Solutions Engineer at Postman

apidays Munich 2025 - Accelerate AI Use Cases with APIs
July 2 & 3, 2025

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Transcript

1. All rights reserved by Postman Inc Johannes Nicolai - johannes.nicolai@postman.com Let’s build, debug and test a magic MCP server in Postman with a few clicks
4. Agenda Function Calling /MCP - Physical Hello World Example Hands-On: Generate and run your own, magic MCP server with Harry Potter & Octocat API Hands-On: Connect your MCP Server to Claude or VSCode Hands-On: Debug, and test your MCP server Q & A 5 4 3 2 1
5. Getting to know you better - Show off hands … Who is using Postman and has an account? Who is using Claude Desktop, GitHub Copilot or Cursor? Who has already heard of MCP and LLM Function Calling? Who has connected to an MCP server? Generated an MCP server? Wrote a custom MCP server? Can run node applications locally or docker locally? Can you access the slides, clone the repo and install deps? Search for “Fun APIs only” on https://postman.com/explore select Octodex-HP-MCP server, check description
7. Function Calling: Connects APIs M to LLMs N - M x N combinations
8. The Integration Challenge: The MN Problem • Each AI model needs unique connections to every service. • This complex setup slows progress and costs more to maintain. • Scaling AI is impossible without a simpler, unified solution
9. Solution: Model Context Protocol MCP • MCP is a standard protocol for AI to use tools and data. • It simplifies integration reducing complexity to MN. • Scaling AI is impossible without a simpler, unified solution
10. MCP  One common protocol for all models and tools M  N https://patel-world.medium.com/mcp-the-usb-c-of-ai-applications-a95dc77fcbf8
11. MCP Momentum A Growing Ecosystem • MCP is backed by Anthropic, Google, Microsoft and OpenAI. • Many companies are rapidly adopting MCP. • A large open-source community supports MCP's growth
12. MCP Architecture How It Works • MCP Hosts are AI apps where users interact. • MCP Clients manage secure connections to Servers. • MCP Servers expose capabilities from existing APIs.
13. MCPGen for Any Collection in the Postman API Network
14. Berlin style Techno Song from MCP Architecture Confluence Page Link to Claude Conversation 🎵🔊
15. Postman as MCP Tool Example - Improve NYT-API and contribute changes back (Official Postman MCP Server)
16. Real world example with Siemens Xcelerator, Backstage, Postman Identifying IOT business cases & API duplicates
17. Cursor / Co-Pilot connected to MCP servers
18. Harry Potter API - https://postman.com/explore - Fun APIs only
19. Octodex API - https://postman.com/explore - Fun APIs only
20. MCP directly embedded into Postman (Agent Mode)
21. MCP Trouble Shooting - https://postman.com/explore - Fun APIs only
22. Our magic example MCP server 🪄 ✨ - Search Fun APIs only
23. Magic MCP Server Demo Repository - Search GitHub for MCP Octocat
24. How to expose the Octocats over an API, generate test cases and performance test it … All in one Demo - Watch Video
25. Adding your own APIs to an existing MCP server (example)
26. Advanced Claude Agent Demo Repo with AWS Bedrock support
27. Example of advanced Image Generation API exposed via MCP
29. MCP Security Best Practices • For Developers: ◦ Prioritize secure credential handling (secrets managers, short-lived creds, RBAC ◦ Supply chain security (tool vetting, trusted scanners) ◦ Environment isolation (containers, network controls) ◦ Safe coding practices (input validation) • For Users: ◦ Use encrypted clients ◦ Enable comprehensive monitoring ◦ Stay vigilant (avoid unknown servers, watch for unusual activity).
30. getmcp.dev : Postmanʼs curated MCP registry with built-in updates and test env
31. Thank you!
32. Donʼt just keep up with the future — build it.
33. MCP Flow Typical Communication Flow • User Interaction: User submits a query to the Host. • Host Processing & Connection: Host identifies required external capabilities and connect to Server(s). • Capability Discovery & Invocation: Client queries Server for available tools and fetches capabilities to use. • Server Execution and Result: Server performs an action and returns results to Client. Client send results to Host.
34. MCP Transport Protocol Overview https://blog.stackademic.com/model-context-protocol-mcp-in-ai-9858b5ecd9ce
35. MCP Message Flow Overview https://www.soa4u.co.uk/2025/03/apis-arent-dead-they-evolve.html
36. MCP Concrete Message Flow Example https://blog.stackademic.com/model-context-protocol-mcp-in-ai-9858b5ecd9ce
37. Postman API Network Worldʼs Largest Public API Hub # of Postman Users 40M # of Public Workspaces 150K # of Public APIs 450K
38. Our new Frankfurt data center on AWS ✨ … magically fast 🪄
39. … also supported by our Backstage integration ✨
40. AI adds more players to the game: Employees who are no dev/domain experts/native speakers can finally participate and developers get a boost, but new challenges arise
41. One rule that will never change though: Garbage In → Garbage Out GenAI will just create larger FrankenstAIn solutions No AI GenAI
42. Thousands of Postman teams/Git repos/Static files lead to API consumer confusion and building “FrankenstAInˮ solutions
43. With a central internal Postman Team and Public API Network • See all “goodˮ lego bricks APIs/collections) available • Discover, Find, Adapt, Evaluate, Collaborate and share in real time with all stakeholders • See what other teams built with the API lego bricks, build & tests API much better • Avoid reinventing the wheel / one off integrations (consumers are no longer forced to become producers because they could not find a proper API • Start to unlock InnerSource benefits and save thousands of hours of confusion and inefficient collaboration