|
| 1 | +""" |
| 2 | +FrozenLake MCP-Gym Implementation - Simplified Version |
| 3 | +
|
| 4 | +This module implements the north star vision for MCP-Gym environments, |
| 5 | +providing a clean, simple implementation of FrozenLake WITHOUT the adapter pattern. |
| 6 | +
|
| 7 | +Key Features: |
| 8 | +- Strict data/control plane separation |
| 9 | +- Data plane: Tool responses contain only observations |
| 10 | +- Control plane: Rewards/termination available via MCP resources (control://reward, control://status) |
| 11 | +- Direct environment handling (no adapter layer) |
| 12 | +- <50% complexity of adapter-based version |
| 13 | +
|
| 14 | +Example usage: |
| 15 | + from frozen_lake_mcp_simplified import FrozenLakeMcpSimplified |
| 16 | +
|
| 17 | + server = FrozenLakeMcpSimplified(seed=42) |
| 18 | + server.run() |
| 19 | +""" |
| 20 | + |
| 21 | +import json |
| 22 | +from typing import Any, Dict, Optional |
| 23 | + |
| 24 | +from gymnasium.envs.toy_text import FrozenLakeEnv |
| 25 | +from gymnasium.envs.toy_text.frozen_lake import generate_random_map |
| 26 | +from mcp.server.fastmcp import Context, FastMCP |
| 27 | + |
| 28 | + |
| 29 | +class FrozenLakeMcpSimplified: |
| 30 | + """ |
| 31 | + Simplified FrozenLake MCP-Gym environment implementing the north star vision. |
| 32 | +
|
| 33 | + This demonstrates the clean, simple API for MCP-Gym environments WITHOUT adapters: |
| 34 | + - Direct environment handling (no adapter pattern) |
| 35 | + - Built-in action parsing and observation formatting |
| 36 | + - Register tools with @self.mcp.tool() decorator |
| 37 | + - Compatible with CondaServerProcessManager |
| 38 | + - Strict data/control plane separation via MCP resources |
| 39 | + """ |
| 40 | + |
| 41 | + ACTION_NAMES = ["LEFT", "DOWN", "RIGHT", "UP"] |
| 42 | + |
| 43 | + def __init__(self, seed: Optional[int] = None, grid_size: int = 4): |
| 44 | + """Initialize simplified FrozenLake MCP-Gym environment.""" |
| 45 | + self.grid_size = grid_size |
| 46 | + |
| 47 | + # Create environment directly |
| 48 | + self.env = self._create_environment(seed) |
| 49 | + self.obs, _info = self.env.reset(seed=seed) |
| 50 | + |
| 51 | + # Initialize control plane state |
| 52 | + self.control_plane_state = { |
| 53 | + "reward": 0.0, |
| 54 | + "terminated": False, |
| 55 | + "truncated": False, |
| 56 | + "info": {}, |
| 57 | + "step_count": 0, |
| 58 | + "total_reward": 0.0, |
| 59 | + } |
| 60 | + |
| 61 | + # Create FastMCP server |
| 62 | + import os |
| 63 | + |
| 64 | + self.mcp = FastMCP( |
| 65 | + "FrozenLake-Simplified-v1", |
| 66 | + host="0.0.0.0", |
| 67 | + port=int(os.environ.get("PORT", 8000)), |
| 68 | + ) |
| 69 | + |
| 70 | + # Register resources and tools |
| 71 | + self._register_control_plane_resources() |
| 72 | + self._register_standard_resources() |
| 73 | + self._register_tools() |
| 74 | + |
| 75 | + def _create_environment(self, seed: Optional[int] = None) -> FrozenLakeEnv: |
| 76 | + """Create FrozenLake environment directly.""" |
| 77 | + if seed is not None: |
| 78 | + desc = generate_random_map(size=self.grid_size, p=0.8, seed=seed) |
| 79 | + else: |
| 80 | + desc = generate_random_map(size=self.grid_size, p=0.8) |
| 81 | + |
| 82 | + return FrozenLakeEnv(desc=desc, is_slippery=False, render_mode="ansi") |
| 83 | + |
| 84 | + def _register_control_plane_resources(self): |
| 85 | + """Register MCP resources for control plane information.""" |
| 86 | + |
| 87 | + @self.mcp.resource("control://reward") |
| 88 | + def current_reward() -> str: |
| 89 | + """Provide current reward information via MCP resource.""" |
| 90 | + return json.dumps( |
| 91 | + { |
| 92 | + "reward": self.control_plane_state["reward"], |
| 93 | + "step_count": self.control_plane_state["step_count"], |
| 94 | + } |
| 95 | + ) |
| 96 | + |
| 97 | + @self.mcp.resource("control://status") |
| 98 | + def current_status() -> str: |
| 99 | + """Provide current episode status via MCP resource.""" |
| 100 | + return json.dumps( |
| 101 | + { |
| 102 | + "terminated": self.control_plane_state["terminated"], |
| 103 | + "truncated": self.control_plane_state["truncated"], |
| 104 | + "step_count": self.control_plane_state["step_count"], |
| 105 | + "total_reward": self.control_plane_state["total_reward"], |
| 106 | + } |
| 107 | + ) |
| 108 | + |
| 109 | + @self.mcp.resource("control://info") |
| 110 | + def current_info() -> str: |
| 111 | + """Provide current environment info via MCP resource.""" |
| 112 | + return json.dumps(self.control_plane_state["info"]) |
| 113 | + |
| 114 | + def _register_standard_resources(self): |
| 115 | + """Register standard MCP resources.""" |
| 116 | + |
| 117 | + @self.mcp.resource("game://initial_state") |
| 118 | + def initial_state() -> str: |
| 119 | + """Provide initial game state as MCP resource.""" |
| 120 | + return json.dumps(self._format_observation(self.obs)) |
| 121 | + |
| 122 | + def _register_tools(self): |
| 123 | + """Register domain-specific MCP tools.""" |
| 124 | + |
| 125 | + @self.mcp.tool( |
| 126 | + name="lake_move", |
| 127 | + description="Move on the frozen lake. Actions: LEFT, DOWN, RIGHT, UP. " |
| 128 | + "Check control://reward and control://status resources for rewards and termination.", |
| 129 | + ) |
| 130 | + def lake_move(action: str, ctx: Context) -> Dict[str, Any]: |
| 131 | + """ |
| 132 | + Move in the FrozenLake environment. |
| 133 | +
|
| 134 | + Args: |
| 135 | + action: Direction to move (LEFT, DOWN, RIGHT, UP) |
| 136 | + ctx: MCP context (proper FastMCP context) |
| 137 | +
|
| 138 | + Returns: |
| 139 | + Dictionary with observation data ONLY (data plane). |
| 140 | + Rewards and termination info available via control plane resources. |
| 141 | + """ |
| 142 | + # Validate action |
| 143 | + if not action or not isinstance(action, str): |
| 144 | + raise ValueError( |
| 145 | + f"Invalid action parameter: '{action}'. " |
| 146 | + f"Must be a non-empty string. Valid actions: LEFT, DOWN, RIGHT, UP" |
| 147 | + ) |
| 148 | + |
| 149 | + action = action.strip().upper() |
| 150 | + |
| 151 | + # Parse action (directly without adapter) |
| 152 | + if action not in self.ACTION_NAMES: |
| 153 | + raise ValueError( |
| 154 | + f"Invalid action '{action}'. Valid actions: {self.ACTION_NAMES}" |
| 155 | + ) |
| 156 | + action_int = self.ACTION_NAMES.index(action) |
| 157 | + |
| 158 | + # Execute environment step with control plane separation |
| 159 | + observation_data = self._execute_environment_step(action_int) |
| 160 | + |
| 161 | + # Add the action to the response for context |
| 162 | + observation_data["action"] = action |
| 163 | + |
| 164 | + # Log the result (control plane state is already logged in _execute_environment_step) |
| 165 | + if ( |
| 166 | + self.control_plane_state["terminated"] |
| 167 | + or self.control_plane_state["truncated"] |
| 168 | + ): |
| 169 | + status = ( |
| 170 | + "🏆 GOAL!" if self.control_plane_state["reward"] > 0 else "💀 HOLE!" |
| 171 | + ) |
| 172 | + print(f"🎮 Game ended: {status}") |
| 173 | + else: |
| 174 | + print(f"🎮 {action} → position {self.obs}") |
| 175 | + |
| 176 | + # Return ONLY data plane information (no rewards/termination) |
| 177 | + return observation_data |
| 178 | + |
| 179 | + def _execute_environment_step(self, action_int: int) -> Dict[str, Any]: |
| 180 | + """ |
| 181 | + Execute environment step and update control plane (directly without adapter). |
| 182 | +
|
| 183 | + Args: |
| 184 | + action_int: Parsed action integer |
| 185 | +
|
| 186 | + Returns: |
| 187 | + Data plane response (observation only, no rewards) |
| 188 | + """ |
| 189 | + # Execute environment step directly |
| 190 | + obs, reward, terminated, truncated, info = self.env.step(action_int) |
| 191 | + |
| 192 | + # Update global observation state |
| 193 | + self.obs = obs |
| 194 | + |
| 195 | + # Update control plane (separate from data plane) |
| 196 | + self._update_control_plane(reward, terminated, truncated, info) |
| 197 | + |
| 198 | + # Return ONLY data plane information (no rewards/termination) |
| 199 | + return self._format_observation(obs) |
| 200 | + |
| 201 | + def _update_control_plane( |
| 202 | + self, reward: float, terminated: bool, truncated: bool, info: Dict[str, Any] |
| 203 | + ): |
| 204 | + """ |
| 205 | + Update control plane state after environment step. |
| 206 | +
|
| 207 | + Args: |
| 208 | + reward: Reward from environment step |
| 209 | + terminated: Whether episode terminated |
| 210 | + truncated: Whether episode truncated |
| 211 | + info: Info dictionary from environment |
| 212 | + """ |
| 213 | + self.control_plane_state["reward"] = reward |
| 214 | + self.control_plane_state["terminated"] = terminated |
| 215 | + self.control_plane_state["truncated"] = truncated |
| 216 | + self.control_plane_state["info"] = info |
| 217 | + self.control_plane_state["step_count"] += 1 |
| 218 | + self.control_plane_state["total_reward"] += reward |
| 219 | + |
| 220 | + # Log control plane update (for debugging) |
| 221 | + print( |
| 222 | + f"🎛️ Control plane updated: reward={reward}, terminated={terminated}, step={self.control_plane_state['step_count']}" |
| 223 | + ) |
| 224 | + |
| 225 | + def _format_observation(self, obs: int) -> Dict[str, Any]: |
| 226 | + """Format observation for MCP response (data plane only, directly without adapter).""" |
| 227 | + return { |
| 228 | + "position": int(obs), |
| 229 | + "grid": self.env.render(), |
| 230 | + } |
| 231 | + |
| 232 | + def run(self, transport: str = "streamable-http", **kwargs): |
| 233 | + """Run the MCP server.""" |
| 234 | + print(f"🚀 {self.mcp.name} Simplified Server Starting...") |
| 235 | + print(f"📡 Transport: {transport}") |
| 236 | + print("🎯 MCP Pattern: Resources for initial state, tools for actions") |
| 237 | + print("🔗 Initial state resource: game://initial_state") |
| 238 | + print("\n🎛️ Control plane resources available:") |
| 239 | + print(" - control://reward (current reward and step count)") |
| 240 | + print(" - control://status (termination status and total reward)") |
| 241 | + print(" - control://info (environment info)") |
| 242 | + print(f"\n📊 Environment: {self.grid_size}x{self.grid_size} FrozenLake") |
| 243 | + print(f"📍 Initial position: {self.obs}") |
| 244 | + |
| 245 | + # Run the server |
| 246 | + self.mcp.run(transport=transport, **kwargs) |
| 247 | + |
| 248 | + |
| 249 | +# Example usage and testing |
| 250 | +if __name__ == "__main__": |
| 251 | + # Test the simplified FrozenLake MCP-Gym environment |
| 252 | + print("Creating simplified FrozenLake MCP-Gym server...") |
| 253 | + server = FrozenLakeMcpSimplified(seed=42) |
| 254 | + |
| 255 | + print("Server created successfully!") |
| 256 | + print(f"Initial observation: {server.obs}") |
| 257 | + print("🎯 NO ADAPTER PATTERN - direct environment handling") |
| 258 | + |
| 259 | + # Run the server |
| 260 | + print("\nStarting MCP server...") |
| 261 | + server.run() |
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