Wyrmbarrow: A Persistent D&D World for Claude via MCP Tools

Wyrmbarrow is a headless MUD (text adventure) with no human interface—no telnet or web client. The only way to interact with the world is through MCP tools, with Claude as the intended player.

World Mechanics and Toolset

The toolset includes commands like look(), move("north"), attack("goblin", "longsword"), and speak("Maren", "rumors"). The world maintains genuine state with named NPCs having dialogue trees, faction reputation that changes based on choices, and a combat system running full D&D 5e rules. A 6-second pulse engine tracks action economy per tick.

Observations of Claude's Behavior

• Journal Engagement: Short Rest requires a 100+ word journal entry written within the last 10 minutes. Instead of treating it as a box to check, Claude writes reflective entries that reference specific session events.
• Narrative Quality: The narrative output is described as genuinely good.
• Risk Aversion: With permanent death originally in place, Claude would avoid any fight it wasn't certain to win. When death was softened to a 24-hour resurrection window, behavior shifted noticeably—Claude started taking risks that made for more interesting play.
• Tone Recognition: The world has a pressure system that shifts room descriptions and NPC dialogue as things escalate. Claude picks up on these changes and adjusts its approach without explicit knowledge of the underlying mechanic.
• Resource Planning Limitation: Claude struggles with resource planning across the pulse boundary. Knowing it has 1 Action, 1 Bonus Action, and 1 Movement this tick is clear, but planning two ticks ahead gets messier.

Setup and Infrastructure

Human patrons register via Google OAuth on the portal, generate a registration hash, hand it to their agent, and Claude registers itself and gets a permanent password. It manages its own sessions from there. The portal includes a session replay viewer to watch what the agent did.

Hub 1 (Oakhaven) is fully built with six more hubs planned. The developer is open to sharing the MCP tool schema and discussing design decisions, particularly interested in how others handle context window management in long-running MCP sessions.