Software Design MCP server

mcp-software-design

An MCP server that teaches and helps apply software-design guidance — the SOLID principles, the OOP pillars, DRY / KISS / YAGNI / meaningful naming / clean code, and the 23 Gang-of-Four design patterns — plus pattern scaffolding and heuristic code-smell detection.

It's the companion to mcp-udacity-commit: same stack (TypeScript, the MCP SDK, stdio transport), same shape (pure logic modules + thin server wiring).

Install

Register it with Claude Code — one line, nothing to clone:

claude mcp add software-design -- npx -y mcp-software-design

Or in an MCP client config:

{
  "mcpServers": {
    "software-design": {
      "command": "npx",
      "args": ["-y", "mcp-software-design"]
    }
  }
}

Why this exists — and its one honest caveat

The commit server can lint: "subject ≤ 50 chars" is objectively checkable. Design principles and patterns are not like that — "does this violate SRP?" or "should this be a Factory?" are judgment calls, not lint rules.

So this server does not pretend to grade your architecture pass/fail. Instead it does the parts that are genuinely reliable, and hands the judgment to the model:

Design analysis is a judgment call, so the "explain/apply helper" is exposed as MCP prompts (which drive the client's model) rather than server code pretending to understand your snippet.

Tools

(principle | solid | oop | pattern | creational | structural | behavioral). solid / oop narrow to the SOLID five / the four OOP pillars.

• listcatalog** { kind? } — list concepts, optionally filtered

pattern (intent, when-to-use, trade-offs, participants). Accepts a slug, name, or alias ("SRP", "open-closed", "pubsub").

• explainconcept** { name } — full guidance for one principle or

pattern; names optionally renames roles to your domain ({ "Product": "Notification" }).

• scaffoldpattern** { pattern, names? } — pseudo-code skeleton for a GoF

method, large class, long parameter list, deep nesting, duplication, and large file. Each finding names the principle it hints at plus a suggested refactor. All thresholds are overridable per call.

• checksmells** { code, …thresholds? } — heuristic scan for long

Resources

naming, and more.

• design://principles — SOLID, OOP pillars, DRY, KISS, YAGNI, meaningful

structural / behavioral.

• design://patterns — the 23 GoF patterns, grouped creational /

caveats.

• design://smells — what check_smells detects, its thresholds, and its

Prompts

principles/patterns, grounded in check_smells + the resources.

• reviewdesign** { code, focus? } — review a snippet against the

pattern (and first judge whether it even fits).

• applypattern** { pattern, code } — refactor a snippet to apply a named

Build from source

Shortened. The full README is on GitHub.