#1165 - MCPJam - kicking the tyres

Introduction 

MCPJam is an open source tool for testing MCP Servers and AI Agent integrations.

An esteemed colleague, Kishore, introduced me to this tool and it certainly does provide better MCP support, compared to postman. So let's try it out. Firstly, here are the OIC based tools, I will be using - 

I enable the MCP Server for the project -

I copy the url generated and open MCPJam -

I generated the bearer token in postman. Now I'm connected and can browse the tools available - 

Now to Playground - 

I validate in OIC project observability - 

One can reduce the number of clients used - 

Let's add some skills - 

The setup is now - 

I enter a new order for an iBike; this one costs more than 50k; well it does have a gold saddle.

now to try more natural language request - 

Here's an update request - 

MCPJam Evaluations

Here we get support for automated testing - the test suite, test cases and the judge!

Click Quick Run -

Naturally, I could add more tests here.

I can also specify the request payload format - 

Here I added - 

{

  "orderNr": "string",

  "customer": "string",

  "customerCountry": "string",

  "product": "string",

  "price": "number",

  "orderStatus": "string"

}

I click Quick Run - 

Check out the Trace - 

The user token count includes everything sent to the model - 2092 tokens. This includes -

The agent token count (total 1251) - relates to the tool invocation - 

So the total costs were - 

Model invocation	Input	Output
Initial agent/tool decision	2,092	231
Post-tool agent response	1,169	82
Total	3,261	313

Such cost related information can be very useful and could be useful for isolating cost/context issues with your MCP server design. 

Testing behaviour of different clients 

As we've already seen, MCPJam supports Claude, ChatGPT and Cursor out of the box.

let's try something vague - "Change order 123 to €4,000."

"Create order 123, but actually change the existing order."

Create order with the following details - 

price = -100

price = 0

price = 50000

price = 50001

price = "50001"

price = null

customerCountry = "Ireland "

customerCountry = "IRL"

customerCountry = "ireland"

customer = NiallC

All 3 agents handled that well -

Summa Summarum

MCPJam is powerful, easy to use and free. What more can I say?

Cerevisia Aestiva

Today's beer is from the Brauerei Kesselring in Marktsteft. 

The brewery is family run since 1688. The water used comes from their own spring and the hops come from Spalt, which is only 10 kms away from me. Despite this pedigree, the beer is disappointing, or should I say forgettable. That's it - not all Franconian beers pass the Commiskey test; despite that - 

Sláinte is táinte.