erd-designer

ERD Designer CLI

Edit .erd files directly with the bundled CLI. No MCP server, VSCode or running app is required. Requires Node.js 20+.

The CLI ships with this skill at scripts/erd-cli.cjs, relative to the directory containing this SKILL.md. This skill is self-contained (Agent Skills format), so it works from any agent that supports skills — e.g. Claude Code and GitHub Copilot CLI. In the examples below, $CLI stands for the resolved path:

CLI=<directory of this SKILL.md>/scripts/erd-cli.cjs

Workflow

1. Discover tools (names and one-line summaries):

   node $CLI list-tools
   

2. Inspect a tool before first use (full description + JSON schema of its arguments):

   node $CLI describe <tool-name>
   

3. Run a tool against a .erd file:

   node $CLI run <tool-name> --file <path/to/file.erd> --args '<json>'
   

   The result is printed as JSON on stdout. Mutating tools save the file in place.
4. Validate a .erd file (e.g. after external changes):

   node $CLI validate --file <path/to/file.erd>
   

Rules

• Do NOT edit .erd JSON by hand; always go through the CLI so referential integrity (column/share/relation IDs) and the canvas layout stay consistent.
• Omit documentId in --args; the CLI injects it from --file automatically.
• Only load the schemas you need via describe; do not dump all schemas at once.
• Files are saved as 4-space-indented JSON, the same format the ERD Designer app writes.
• The VSCode extension reflects CLI edits automatically while the file is open; no reload is needed. The browser app (IndexedDB) does not — re-import the file after CLI edits.
• Creating a brand-new .erd file is done in the ERD Designer app (it configures the target database type). The CLI edits existing files.

Typical recipes

• Add a table with columns: run add-table, then run add-columns-to-table with the returned tableId.
• Relate two tables: look up ids via run list-tables, then run create-relation.
• Review a design: run list-tables (summaries) or run find-table (full detail).
• Generate SQL: run export-ddl.

.erd format (background only)

A .erd file is a single JSON document containing tableViewModels (tables + canvas positions), columnModels / columnShareModels (columns; shares hold the type definition and can be reused by multiple columns), relationViewModels, memos and database settings. IDs cross-reference between these arrays, which is why manual edits are unsafe.

Google Drive / browser users

• Files stored in Google Drive can be edited locally through Google Drive for Desktop: point --file at the synced local path.
• The browser app (IndexedDB) is not reachable from the CLI; export the .erd file first, edit it, then import it back.