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AI data modeling with Claude and MCP

EntityModel.com is built so an AI assistant can work on a model safely. Models are plain JSON with a documented format, and agents change them through proposals: lists of typed changes you review, edit and accept in the app, as one undoable step.

There are three ways in, depending on how you run it.

Copy and paste with claude.ai (any mode)

Design with Claude on the home page works on entitymodel.com with no setup. The app sends nothing anywhere; you copy and paste.

  1. Optionally describe the model or the change ("a subscription billing model with plans, invoices and payments"), then click Copy prompt. The prompt holds the instructions, the model file format and your current model.
  2. Paste it into Claude. Open Claude opens it for you.
  3. Paste Claude's reply back, or open the .json file it made. The dialog finds the JSON and lists what will change: entities and attributes added, removed or changed, relationships, and the validation result.
  4. Click Apply changes. Your layout is kept, new entities are placed automatically, and ⌘Z undoes the whole change.

To change an existing model, export it (Export → Model file), attach it in Claude, and open the result with Open model file.

If you do this often, download the EntityModel.com skill (entity-modeler-skill.zip) from the same dialog and upload it once under Customize → Skills in Claude. After that, attach your model file and ask for changes.

Ask Claude in the app (local mode)

When you run EntityModel.com locally and the Claude Code CLI is installed, the top bar shows Ask Claude (⌘J).

  • Describe a change: "add a Contract entity linked to Supplier", "derive a physical model for Databricks", "work through the open review comments".
  • The run streams into the panel and uses your current tab and canvas selection as context.
  • Claude answers with a proposal. In the review you see each change, can untick the ones you don't want, compare the before/after diff and the validation result, then Accept.
  • Claude runs headless with only the EntityModel.com tools (no shell, no file editing), under your own Claude Code login.

MCP server for any agent

node bin/em.mjs mcp is a Model Context Protocol server. The repository's .mcp.json registers it for Claude Code; any MCP client can use it.

Purpose Tools
Read and check get_model, get_entity, search, validate, list_tabs
Transform and generate diff_tabs, migration_sql, export, docs, derive_tab, import_ddl, pull_schema, sync_tabs, auto_map
Change propose_changes, fix_issues, propose_terms
Review list_comments, reply_comment, list_proposals, withdraw_proposal
Glossary search_glossary

Changes become proposals in models/<id>/proposals/. A banner in the app offers them for review, or handle them from the terminal:

node bin/em.mjs proposals sales                    # list pending proposals
node bin/em.mjs proposals sales --accept <pid>     # or --reject, --show
node bin/em.mjs apply sales ops.json [--apply]     # the same typed operations without MCP

Start the server with --allow-apply to add apply_changes, which edits directly without review, for automation you trust.

Claude Code skills

The repository ships three Claude Code skills in .claude/skills/:

Skill What it does
entity-model-design Design or extend a model from requirements, DDL, CSV headers or spreadsheets
entity-model-review Validate and critique a model before sharing it
entity-design-doc Write the data-model section and tables of a design document

Put source material in models/<id>/inputs/ and ask, for example: "Design a Customer and Order model from the DDL in models/acme/inputs." To use the skills in the Claude desktop app, run npm run skills:package and upload the zips from cowork-skills/.

Tips for good results

  • Give the agent your source material: DDL, CSV headers, a requirements document, interview notes.
  • Ask for one coherent change at a time ("model the billing subject area") rather than the whole enterprise at once.
  • Set naming standards first; agents follow them, and validation catches what they miss.
  • Review the proposal's validation result before accepting.

Frequently asked questions

Can AI design a database schema for me?

Yes. Describe the domain in Design with Claude or Ask Claude, and Claude writes an EntityModel.com model with entities, typed attributes, keys, reference lists and relationships. You review it on the diagram and export SQL DDL for your database.

Does the AI change my model without asking?

No. Claude's changes arrive as a proposal that lists each change with a diff and the validation result. Nothing is applied until you accept it, and accepting is one undoable step.

Does EntityModel.com send my model to an AI service?

Not by itself. On entitymodel.com you copy and paste the prompt into Claude yourself. Ask Claude in local mode runs the Claude Code CLI on your machine under your own login.