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What it is for

The Playground tab on the server detail page lets you talk to a real model that is connected to your server. For every answer you see which tool the model picked, the parameters it sent and the result your tool returned. Use it to:
  • Check that your tool names and descriptions lead the model to the right tool
  • See which parameters the model fills in, and whether it understands the optional ones
  • Try a tool end to end after you publish it, without setting up an AI client
  • Compare how Claude and OpenAI models use the same tools
Run in the tool editor tests one tool with values you type. The Playground tests the whole server the way an AI client uses it: the model decides which tools to call, in what order and with which values.

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Use your own API key

The Playground uses your own key from Anthropic or OpenAI, and the provider bills the usage to your account.
  • The key is sent straight from your browser to the provider. MCPCore never receives or stores it.
  • By default the key is forgotten when you leave the page. Tick Remember the key in this browser tab to keep it until the tab is closed.
  • Anthropic and OpenAI each have their own key field. Switching the provider starts a new chat.
Get a key from the Anthropic Console or the OpenAI platform.

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Chat with your tools

1

Open the Playground tab

On the server detail page, open the Playground tab.
2

Pick a provider and model

Choose Anthropic or OpenAI, then pick a model from the list. See Models.
3

Enter your API key

Paste the key into the key field.
4

Ask something

Type a question, or click one of the suggestions built from the descriptions of your first tools. The model answers and calls your tools when they help.
5

Inspect the tool calls

Every tool call appears as a card in the answer, for example Called get_order. Click it to see the Parameters the model sent and the Result your tool returned.
The model remembers the earlier messages of the chat, so you can ask follow-up questions such as “and the one before that?”. Click New chat to start over.

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Models

Which models your key can use depends on your provider account. If a model is not available for your key, the provider returns an error and the chat shows it.
To check that your tool descriptions work for every AI client, try the same question with a smaller model such as Claude Haiku 5.5 or GPT-6 Luna. If a small model picks the right tool, larger models will too.

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Reading a tool call card

A failed tool call is not the end of the answer: the model sees the error and usually explains it or tries again with other values. That tells you how well your error messages help an AI client.

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Which tools the model sees

  • Every active tool on the server, in its live version. Drafts are not used until you publish them.
  • Tools marked Deletes or overwrites data in their behavior are turned off, see below.
  • The model reads exactly what an AI client reads: tool name, description and parameter schema.

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Safety

  • Tool calls run against your live server, your APIs and your databases, just like calls from any other AI client. They appear in Traffic Logs and Analytics, and count as normal requests to your server.
  • Tools marked as Deletes or overwrites data are turned off by default. When the server has such tools, a switch above the chat reads Allow N tools that delete or overwrite data. Turn it on only on purpose. While it is on, the Playground warns “These tools run for real against your API and data.”
  • Tools marked Changes data or with no behavior set are available. Set the behavior of every tool that writes data, so the Playground and AI clients can treat it carefully.

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Server types

The provider connects to your server from its own cloud over the public internet. The server must be active and its endpoint reachable.

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Messages and errors

When a request fails, your message is put back into the input so you can send it again.