PharoAgent

PharoAgent is a lightweight TCP server for Pharo that lets external tools send Smalltalk snippets for evaluation and trigger browser navigation commands.

To install stable version of PharoAgent in your image you can use:

Metacello new
  githubUser: 'pharo-llm' project: 'pharo-agent' commitish: 'X.X.X' path: 'src';
  baseline: 'LLMPharoAgent';
  load

For development version install it with this:

Metacello new
  githubUser: 'pharo-llm' project: 'pharo-agent' commitish: 'main' path: 'src';
  baseline: 'LLMPharoAgent';
  load.

Start the agent

In the Playground, run:

PharoAgent start

To use a custom port:

PharoAgent startOn: 4044

Restart cleanly

If you reloaded the class and want a fresh restart, run:

PharoAgent stop.
PharoAgent resetDefault.
PharoAgent start

Evaluate an expression

echo "3 + 4" | nc localhost 4044

Expected output:

7

Open a class browser

echo "OPEN_CLASS_BROWSER String" | nc localhost 4044

Talk to the live image from Claude Code, Codex, or Qwen (MCP)

PharoAgent ships with an MCP server (LLM-Pharo-MCP) that exposes the running image over HTTP so CLI agents like Claude Code, Codex, or Qwen Code can talk directly to it — evaluate Smalltalk, open browsers, read class and method source — without spawning a fresh headless Pharo per call.

Start the MCP server

In a Playground:

PharoAgent startMcp.
"or on a custom port"
PharoAgent startMcpOn: 4046.

The server listens on http://localhost:4046/mcp by default. Override with the PHARO_MCP_PORT environment variable before launching the image.

To stop it:

PharoAgent stopMcp.

Configure your CLI agent

The repo ships a ready-to-use .mcp.json at the root:

{
  "mcpServers": {
    "pharo": {
      "type": "http",
      "url": "http://localhost:4046/mcp"
    }
  }
}

Claude Code picks it up automatically when started from the repo root. For Codex, Qwen or any other MCP-speaking client, point its MCP config at the same URL.

Registered tools

Tool	Description
pharo_eval	Evaluate a Smalltalk expression, returns its printString
pharo_open_class_browser	Open a System Browser on the given class
pharo_open_method_browser	Open a System Browser on ClassName>>selector
pharo_class_source	Return the class definition and its selector list
pharo_method_source	Return the source of a single method

Registered resources

URI	Description
pharo://system/info	Pharo version, package count, image path
pharo://class/{className}	Class definition + method list
pharo://method/{className}/{selector}	Source of a single method