Erd Editor vs Mellos Mapping
A side-by-side look at the Erd Editor and Mellos Mapping MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
Verdict: choose Erd Editor for developer tools work as a local process; choose Mellos Mapping for developer tools as a local process. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose Erd Editor when
- You need dedicated capabilities in the Developer Tools domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: No auth required.
- You want tools like
erd_list_documents, erd_open_document, erd_save.
Choose Mellos Mapping when
- You need dedicated capabilities in the Developer Tools domain.
- You prefer a local stdio subprocess transport.
- You want tools like
mmap_declare, mmap_update, mmap_read.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | ||
|---|---|---|
| Category | Developer Tools | Developer Tools |
| Quality signal | 71/100 · Great | 67/100 · Great |
| Install command | Confirmed | Confirmed |
| Transport | Local subprocess (stdio) | Local subprocess (stdio) |
| Auth | No auth required | Not declared |
| Pricing | Free | Not declared |
| Required env vars | None listed | None listed |
| Verified owner | Community listing | Community listing |
| GitHub stars | 1,729 | 114 |
| Directory activity | 0 views 0 installs 0 upvotes | 2 views 0 installs 0 upvotes |
| Tools | 77 | 8 |
| Full listing | View Erd Editor | View Mellos Mapping |
Tools & capabilities
Erd Editor tools 77
erd_list_documentsLists ERD documents with path, open, active, dirty and readonly. With an editor serving the working directory (the VS Code extension, the Obsidian plugin or the JetBrains IDE plugin) it lists that editor's, every open project's in a JetBrains IDE; otherwise the ERD files under the working directory.erd_open_documentOpens a document for editing, in the ERD editor of the editor that serves it, if one does (the VS Code extension, the Obsidian plugin or the JetBrains IDE plugin). With create it makes the file first if missing; a name with no extension gets .erd.json.erd_saveSaves a document an editor holds to disk. VS Code keeps edits unsaved until this is called; Obsidian and JetBrains IDEs save them as they save the user’s edits, and this writes them at once. On disk, with no editor, edits are written at once and this does nothing.erd_undoReverts the last edit this agent made to the document, never the user’s edits. Calls that made no undo entry are skipped and named.erd_redoApplies again the edit erd_undo last reverted.erd_readReads a document as a snapshot, as DDL, as its raw JSON or, with the scripts format, its before and after scripts alone. The sql format of the whole document includes the document's before and after scripts. The sql format with tableIds, tableNames or groupNames gives the DDL of just those tables, the way to read a large schema; a read too large for one answer is refused with how to narrow it. For ids and details prefer erd_list and erd_get. Change a document only through the erd_ tools, never by writing its file.erd_listLists a document: its settings and counts, then a page of tables, each with its id, position and size on the ERD canvas (the width approximate, the height exact), with their indexes and relationships (each relationship once, with one of its tables) and, for a table in a table group or with a logical name, its groupId or logicalName; after the tables come the table groups, the memos, then the rows of the domain, term and word dictionaries, each with its name and what it gives a physical name or column. A small schema fits in one page. On a larger one, nextOffset and note say how to go on: query finds tables by a word, namesOnly lists every table name in a call or a few. Columns, comments, memo text, the tables of a group and every field of a dictionary row come from erd_get; the foreign keys a table holds, from erd_read sql with tableNames.erd_getGives the entities named, in full: tables with their columns and size, relationships with their columns, indexes with their columns, memos with their text, table groups with their tables, and words, terms and domains with every field. Ids and names that name nothing live are listed in missing; ids one answer has no room for are listed in notReturned, to ask for again.erd_list_checksLists what the word, term and domain dictionaries find, as the Checks sheet of the editor's Dictionary tab does, and changes nothing. Errors: a name two rows of one dictionary share, a link to a domain the document does not list, a forbidden word in a logical name or a term's name. Warnings: a word no dictionary lists, a synonym used for a standard word, each in a logical name or a term's name, a physical name other than the one the term of its logical name gives, a column type other than its domain's. Each check names its target (a table, a column with its table, or a word, term or domain row) with its names, the field read, the text found and, where the dictionaries have them, the suggestions to use instead, and counts gives each code's total. The words, terms and domains come first in sheet order, then each table and its columns in document order. With no dictionary row nothing is checked. A long list comes a page at a time: pass nextOffset, or list again from offset 0 after fixing some, since a fixed check leaves the list.erd_add_tableAdds an empty table at a free spot and returns its id in createdIds. Name it with erd_change_table_name.erd_remove_tableRemoves a table with its columns, indexes and every relationship that touches it.erd_change_table_nameRenames a table. The name is then its own: nameDerived goes off, so a later logical name leaves a name that is not empty as it is.- +65 more on the listing page
Mellos Mapping tools 8
mmap_declareGrow the Mellos map: set the title and diagram kind, add layer bands, lanes and groups (labeled subsystems within ONE band — declare them when a single band grows crowded, roughly five or more nodes in that band; a group must be a strict subset of its band, and a map spread thin across many bands needs none), add nodes, add dependency edges. Declare the missing design after reading existing pages with mmap_read; reuse verified nodes. Edges must point strictly downward (a node may only use nodes on lower layers); the batch is all-or-nothing. Title and kind can also be changed with mmap_update; this legacy form remains supported. Revising what already exists (moving, renaming, relabeling, clearing) is mmap_update.mmap_updateThe revision tool, all-or-nothing. Record progress on nodes: in-progress when starting a node (the pane spins), done with evidence when its verification passes, regressed with evidence when a done node breaks. Revise what the ghost design got wrong: move a node to another band, join or leave a group or lane, rename a band (or re-rank it, which reorders the whole map), relabel a group or a lane. Every clearable field takes null to empty it — that is how a field is cleared, never an empty string. Bands, groups and lanes are applied before the node updates, and within one node update `layer` moves the node before its other fields. The map is a ledger: report honestly, it never blocks you.mmap_readRead existing pages before creating a map. Returns structured IDs, revisions and bounded results. pages lists summaries; map reads page metadata/context; nodes/edges/layers/groups/lanes read editable records; neighborhood reads related nodes; changes compares saved source hashes with local files. New conversations and compacted context should resume the existing effort. mmap_view remains the picture.mmap_batchAtomically combine additions, updates and removals on ONE page. Checks the final graph, so a coordinated move or edge replacement needs no intermediate saves. Read IDs and revision with mmap_read first. Cross-page deletion is excluded.mmap_removeRemove edges, nodes, groups and empty layer bands (in that order, all-or-nothing). Removing a node also removes every edge touching it; removing a group merely ungroups its members. Use when the ghost design turns out wrong — the map is a hypothesis, revising it is honest work. `pages` is the other scale: it DELETES whole page files, so a finished effort can be cleaned up instead of accumulating tabs forever. A bare `{pages: ["slug"]}` with no other field is the normal form; combined with map edits, the edits are applied first and the pages are deleted after. The deletion is permanent and cannot be undone, so delete only pages whose effort is over — and only ever with the user behind it. An unknown slug is refused with the project's real page list (naming a page that does not exist is a typo, not a request). The default page has no slug and is not deletable here. A node elsewhere still pointing at a deleted page with `submap` stays legal — a submap reference has no existence invariant — but it has nowhere to dive until the page comes back.mmap_setupGet or set the mapping policy — WHEN the assistant opens a Mellos map. Call with no arguments to read it: the reply names the policy chosen for the USER (every project), the one this PROJECT overrides it with if any, and which of them is in effect. If it reports "not set", ask the USER to choose (never pick for them): always = map every structured task — workflows, designs, architecture, technical dependencies; complex = map only medium or complex tasks — several modules, a new subsystem, roughly an hour or more; on-request = map only when the user explicitly asks. Then call again with their choice to persist it. It defaults to user scope, which is the normal one — the question is about how someone works, so it is asked once ever, not once per repository. Pass scope: "project" only when the user wants THIS project to differ from that habit. The policy guides you; it never blocks the tools, and an explicit user request for a map always wins.mmap_viewRender the current Mellos map as monochrome text — the same picture the split-pane watcher shows live. Use it to check the map state or to show it inline in conversation. Every response ends with a `pages:` line naming the pages this project actually has and which one you are looking at, so this is also how you discover whether a map exists at all and under which slugs — never probe the files.mmap_openFor automatic display beside the current ChatGPT desktop conversation in Codex mode, use surface: "web-terminal", then call open_in_codex with the returned browser hostOpen object. No paste or Computer Use is needed. For the native host terminal, use surface: "codex-terminal": prepare absolute watcher commands for the current project, then ask the host to open its right terminal. This does not launch the watcher or type into that terminal. Agent exec PTYs cannot be attached using their numeric session ids. For a document panel, use surface: "markdown": generate MD + SVG files, enable automatic preview updates after successful map writes, then use the HOST file-opening tool to display the returned absolute Markdown path on the right of the current conversation. Generated does not mean visible: this server cannot open or observe the desktop side panel. For interactive maps, choose surface: "web": start or reuse a project-local web viewer and pass the returned URL to the host browser-opening tool. Markdown and terminal remain available. The default surface is "terminal", preserving the terminal workflow. Put the live map on the user's screen: a terminal pane beside this conversation that redraws on every write. Call it whenever a result says `pane: CLOSED` — and do NOT ask permission first, because a user who has set a mapping policy has already said they want to see the map. With a pane already open this RETARGETS it to `page` instead of opening a second one, so it is also how you show the user a particular page when they ask for one. It never closes a pane: taking the map off the screen belongs to the user (the `q` key in the pane, or typing `mmap` in a terminal). The reply says whether a pane actually reported itself in afterwards, not merely that a command was run. Automatic terminal opening supports Windows Terminal, tmux on Linux/macOS, and Pebrel, which splits the conversation's own pane. omp (Oh My Pi) has no side panel of its own: there the routes are this same terminal pane (a Windows Terminal split, or a tmux split on Linux/macOS) and the web viewer, whose URL the session opens with its own browser tool. If opening fails, relay the reason and copyable command; retry only after the environment changes or the user asks.
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
Erd Editor
{
"mcpServers": {
"erd-editor": {
"command": "npx",
"args": [
"-y",
"@dineug/erd-editor-mcp"
]
}
}
}
Mellos Mapping
{
"mcpServers": {
"mellos-mapping": {
"command": "npx",
"args": [
"-y",
"mellos-mapping"
]
}
}
}
Frequently asked questions
Erd Editor is categorized under Developer Tools and uses a local stdio subprocess. Mellos Mapping belongs to Developer Tools and uses a local stdio subprocess. Pick Erd Editor for developer tools work and Mellos Mapping for developer tools.
Copy the mcpServers block from the config section on this page into your client's config (for example claude_desktop_config.json or ~/.cursor/mcp.json), then fully restart the client.
Erd Editor is listed as free. Auth: no auth required. Mellos Mapping has no declared pricing — check the project's own site. If a server needs environment variables such as API keys, define them under the env key in your client's MCP config.
Yes. MCP clients support multiple servers: add erd-editor and mellos-mapping as separate keys in the same mcpServers object, and your assistant will call tools from either one.
On AllMCPs, Erd Editor has a quality signal of 71/100 (Great) with 0 views, 0 installs and 1,729 GitHub stars. Mellos Mapping has 67/100 (Great) with 2 views, 0 installs and 114 GitHub stars.