ClaudeSmalltalk MCP Server

MCP server for AI interaction with live Smalltalk images

Local serverstdioPython

What is the ClaudeSmalltalk MCP server?

ClaudeSmalltalk MCP server is a locally run integration for AI assistants that speak the Model Context Protocol. MCP server for AI interaction with live Smalltalk images.

What you get

Connect Claude Desktop to a live Smalltalk programming environment. Browse classes, evaluate expressions, define methods, and run autonomous code review — all against a running Squeak or Cuis image.

Setting it up

The server ships on PyPI as httpx, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

What the assistant can call

Once ClaudeSmalltalk is connected, these are the calls the assistant has available:

  • smalltalk_evaluate — Execute Smalltalk code and return result
  • smalltalk_browse — Get class metadata (superclass, ivars, methods)
  • smalltalk_method_source — View source code of a method
  • smalltalk_define_class — Create or modify a class definition
  • smalltalk_define_method — Add or update a method
  • smalltalk_delete_method — Remove a method from a class
  • smalltalk_delete_class — Remove a class from the system
  • smalltalk_list_classes — List classes matching a prefix
  • smalltalk_hierarchy — Get superclass chain
  • smalltalk_subclasses — Get immediate subclasses
  • smalltalk_list_categories — List all system categories
  • smalltalk_classes_in_category — List classes in a category

Configuration and credentials

You will need one environment variable: SMALLTALK_MCP_CONFIG. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

Before you rely on it

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • With 14 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch ClaudeSmalltalk.
  • MCP clients confirm each tool call by default. Leave that on until you have watched what the claudesmalltalk mcp server does with a few real requests.

Choosing this one

Plenty of developer tooling servers cover similar ground. The differences that matter in practice are scope of access and how much setup stands between you and a working tool call. ClaudeSmalltalk's toolset — smalltalk_evaluate, smalltalk_browse, smalltalk_method_source and 11 more — is a fair guide to whether it matches your workflow. It is maintained by johnmci; worth a glance at recent repository activity before you build anything load-bearing on it.

We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Available tools

ToolWhat it does
smalltalk_evaluateExecute Smalltalk code and return result
smalltalk_browseGet class metadata (superclass, ivars, methods)
smalltalk_method_sourceView source code of a method
smalltalk_define_classCreate or modify a class definition
smalltalk_define_methodAdd or update a method
smalltalk_delete_methodRemove a method from a class
smalltalk_delete_classRemove a class from the system
smalltalk_list_classesList classes matching a prefix
smalltalk_hierarchyGet superclass chain
smalltalk_subclassesGet immediate subclasses
smalltalk_list_categoriesList all system categories
smalltalk_classes_in_categoryList classes in a category
smalltalk_save_imageSave the current image in place
smalltalk_save_as_new_versionSave image/changes as next version number

How to install the ClaudeSmalltalk MCP server

{
  "mcpServers": {
    "claudesmalltalk": {
      "command": "uvx",
      "args": ["httpx"],
      "env": {
        "SMALLTALK_MCP_CONFIG": "your-value"
      }
    }
  }
}

Add to claude_desktop_config.json, then restart Claude Desktop.

Configuration

VariableDescriptionRequired
SMALLTALK_MCP_CONFIGConfiguration value read at startup.Optional

Example prompts to try

  • Use ClaudeSmalltalk to smalltalk evaluate.
  • Use ClaudeSmalltalk to smalltalk browse.
  • Use ClaudeSmalltalk to smalltalk method source.

Frequently asked questions

It connects ClaudeSmalltalk to MCP-compatible AI assistants such as Claude and Cursor, exposing 14 tools (smalltalk_evaluate, smalltalk_browse, smalltalk_method_source, and more) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with ClaudeSmalltalk directly.