EasyChatDM - Demonstrates creating a simple MCP Server tools

EasyChatDM - Demonstrates creating a simple MCP Server tools

Example MCP Server tools for playing D&D with generative AIs. These tools are oracles that are used to determine random yes/no questions but also descriptions, events, NPCs, etc. They are "random tables" to use when you want to introduce some uncertainty, twists and turns, and randomness to your gaming. This project is for educational purposes, so little attention is given to good code design.

These tools are MCP Server tools that will work with Claude desktop and other MCP Clients. They're written in Spring AI MCP. This project is for education, so no consideration is given to good design. Instead, the code is written to make it easy to follow step-by-step how to create tools.

Running it

You should copy over the contents of contents of src/main/easychatdmdir/prompts/ to ~/.easychatdm. These are files for prompts, oracles, etc. uses.

Database configuration

The DM Journal now persists to a database instead of plain JSON files. Local runs default to SQLite with the database file stored under ~/.easychatdm/easychatdm.db. Switching between SQLite and PostgreSQL is controlled entirely through system properties or environment variables.

Available properties

Property	Default	Description
easychatdm.dir	${user.home}/.easychatdm	Base directory for prompts/oracles and, for SQLite, the database file location.
easychatdm.db.type	sqlite	Selects sqlite (local file) or postgres (remote database).
easychatdm.db.sqlite.path	(derived from easychatdm.dir)	Overrides the full path to the SQLite database. If set to a directory, the file name below is appended.
easychatdm.db.sqlite.file-name	easychatdm.db	Name used when creating the SQLite database under the resolved directory.
easychatdm.db.sqlite.pool-size	1	HikariCP pool size when using SQLite (typically keep at 1).
easychatdm.db.postgres.url	(required when db.type=postgres)	JDBC URL for the PostgreSQL instance.
easychatdm.db.postgres.username	(required when db.type=postgres)	Database username.
easychatdm.db.postgres.password	(empty string)	Database password.
easychatdm.db.postgres.pool-size	4	HikariCP pool size when using PostgreSQL.
easychatdm.journal.export-files	true for SQLite, false for Postgres	Mirrors journal contents to JSON/Markdown files when enabled.

For Cloud Foundry (or any remote deployment) set the system properties with JAVA_OPTS, for example:

JAVA_OPTS: >-
  -Deasychatdm.db.type=postgres
  -Deasychatdm.db.postgres.url=${JDBC_DATABASE_URL}
  -Deasychatdm.db.postgres.username=${JDBC_DATABASE_USERNAME}
  -Deasychatdm.db.postgres.password=${JDBC_DATABASE_PASSWORD}

Acknowledgements

• Some oracle values and schemes used from JeansenVaars's Play By Writing, and PUM, GUM, etc. systems.

More

See the ChatDM project for a more complex, feature-ful somewhat better designed version of this EasyChatDM.

Here are some videos going over the project:

1. Part one of a video series
   where I build a very simple MCP too-land.
2. In part two of the video series where I build a file-based oracle and go over how to use the logs Claude makes and start doing your own logging.
3. In part three, I build an MCP Resource to serve as a DM Journal to persist game information between play sessions.
4. Finally, I get around to making an MCP Prompt, which is really exciting.
   This is the first glimpse at something that feels "agentic."

Keep an eye on the playlist for the rest of the videos as they come out.

References

• Enabling developer mode in Claude desktop
• The ChatDM project - more sophisticated ChatDM tool that's better designed, has more tools, etc.
• Dan Vega's MCP examples.
• Plot Unfolding Machine - some prompts are based on JeansenVaar's PUM system, which is CC BY-NC-SA 4.0.
• My experience playing D&D with ChatGPT and generative AI - video notebook of how I play D&D with the AIs.

Versions

• 0.0.4 - DM Journal stored in SQLite by default, switchable to PostgreSQL via system properties.
• 0.0.3 - relativly stable, before converting over to use services for DM journal storage. This version still depends on file access.