mcp-toolkit

MCP servers for React + TypeScript development automation. Works with Claude Desktop, Cline, Cursor — and as plain CLI scripts — one protocol, zero duplication.

59 tools across 9 categories — component scaffolding, code quality, a full CRUD-feature factory, CRA→Vite migration, and more. Every tool ships as its own MCP server, built and tested independently.

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Why this exists — the token math

Here's the thing nobody tells you when you start building agentic workflows: the loop itself is what's expensive, not the model. An agent working without any composed tools does everything the slow way — read a file, think, write a file, read it back to check its own work, repeat — and every single one of those turns re-sends the whole conversation so far as input tokens. By the time you're 20 steps into a real multi-file task, that resent context alone can be running 50K+ tokens per call. It adds up fast, and it's not really about which model you're using.

I didn't just take that on faith — a few sources back it up with real numbers. LeanOps measured agent loops running about 3.2× the tokens of a single direct call at 5 steps, ~30× at 50 steps, and past 100× once you're deep into a typical build-and-debug session — because re-sent context is roughly 62% of the bill. Vantage found similar: real agentic sessions run an input-to-output ratio around 25:1 (a direct call is closer to 1:1), with a 50-turn session routinely hitting a million input tokens, and non-agentic usage on comparable work costing something like 200× less per interaction on the same team. And a recent arXiv paper on agentic tokenomics puts agentic tasks at roughly 1000× the tokens of single-turn work, with up to 30× variance run to run on the exact same task — so it's not just expensive, it's unpredictable.

That's the problem this toolkit's composed tools are built to get rid of. workflow-runner's schema_to_feature and cra-to-vite don't add one more tool call into an agent's existing loop — they replace what would otherwise be 7 or 8 separate read/write/verify turns with a single in-process call that runs the whole generator or migration pipeline and hands back the finished result. That's the "50-turn loop collapses into 1 call" shape the research above says saves 10–100×, which is a very different thing from just bolting one extra tool onto an unchanged loop (that only gets you the 20–40% range).

To keep myself honest, I also ran a real, measured benchmark rather than just trusting the theory — ax-benchmark, 6 tasks, claude -p running headless, three arms (agent alone, agent with one MCP tool call added into its loop, and the tool called directly with no agent at all). This is a conservative baseline on purpose, since it only tests adding a single tool call into an otherwise unchanged loop, not the deeper pipeline collapse described above:

	Agent alone	Agent + one MCP tool	Tool called directly
Analysis tasks (review, a11y, legacy-code)	baseline	~41% lower cost	~100% free, ~15× faster (when in scope)
All 6 tasks, blended	baseline	~19% lower cost	—
New code (component, tests)	baseline	roughly cost-neutral	not applicable to novel work

Two things worth being upfront about: cost is the fair metric here, not wall-time — the agent-alone arm ran headless with no shell access and over-explored on open-ended tasks, which inflated its time without touching its actual cost. And on small, novel, single-file work, the overhead of the tool's structured output can offset what it saves — the real win shows up on repetitive, mechanical, multi-file work, which also happens to be exactly where the multi-turn-loop tax above hits hardest.

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Install

Published on npm as mcp-react-toolkit. No clone or build required:

npx mcp-react-toolkit --list            # list all 59 tools
npx mcp-react-toolkit legacy-analyzer   # run one as an MCP server (stdio)

Add it to Claude Desktop / Cursor / Cline:

// claude_desktop_config.json
{
  "mcpServers": {
    "legacy-analyzer": { "command": "npx", "args": ["-y", "mcp-react-toolkit", "legacy-analyzer"] }
  }
}

Swap in any tool name from npx mcp-react-toolkit --list. Restart your client and the tool appears.

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Interactive dashboards

Most MCP tools return raw JSON. These return that JSON plus an interactive HTML dashboard — health score, sortable issue triage, light/dark toggle, and one-click fix actions that call other tools in the toolkit. One self-contained artifact, no server, no external requests:

Where you run it	What you get
Claude Desktop (MCP Apps)	Renders inline in the conversation (sandboxed iframe)
Claude Code · Cursor · CLI	JSON plus a clickable file:// link to the same dashboard
Any browser	The same HTML, standalone

Analysis tools (legacy-analyzer, component-reviewer, dep-auditor, etc.) get an audit view — grade, category cards, filterable issue table. Generators (component-factory, code-modernizer, etc.) get a result view — files created/changed, diffs, follow-ups. Powered by the internal @mcp-showcase/ui-kit package: dependency-free, ~30 KB per report.

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Tools

Component Development

Tool	What it does
component-factory	Scaffold React components from 41 shadcn/ui templates — with tests + Storybook
component-reviewer	Audit TypeScript errors, a11y issues, test coverage — graded A+ to F
component-fixer	Auto-fix broken imports, missing deps, inline style refactors
component-improver	Extend a component with variants, comprehensive stories, and edge-case tests
storybook-generator	Auto-generate Storybook stories — Default, variants, sizes, callbacks, play functions

Code Quality & Modernisation

Tool	What it does
typescript-enforcer	Scan for any types, unsafe casts, missing modifiers — 7 rules, scored 0–10
accessibility-checker	WCAG 2.1 audit — alt text, label associations, ARIA roles, keyboard navigation
a11y-autofixer	Apply safe a11y fixes (img alt, blank rel, htmlFor, tabIndex)
quality-pipeline	5-stage audit (tests · types · perf · a11y · design tokens), graded A–F
review-gate	Static A–F quality gate for generated/changed code
enforce-design-tokens	Flag hardcoded colors/spacing/radii/shadows, suggest tokens, grade A–F
render-analyzer	Detect unnecessary re-renders, missing memo, inline objects/functions
performance-audit	Memory leaks, heavy imports, unoptimized images, deep nesting
bundle-budget-guard	Gate gzipped asset sizes against per-pattern budgets — fail CI on regressions
code-modernizer	AST-based JS/JSX → TypeScript conversion, PropTypes → interfaces
react-compiler-migrator	Flag redundant useMemo/useCallback/memo for the React 19 Compiler
codemod-runner	Generic regex codemod engine + named built-ins; dry-run by default
refactor-executor	Execute refactor plans safely — move/rename/split, update imports, rollback
redux-state-analyzer	Audit Redux for anti-patterns (selectors, mutations, RTK Query migration hints)
api-contract-differ	Diff two API snapshots → breaking vs additive changes — CI gate against breaks
i18n-extractor	Scan JSX for hardcoded strings → i18n keys + message catalog
generate-tests	Analyze a TS/React source file and generate a Vitest test suite
test-gap-analyzer	Find unimplemented functions, uncovered branches, missing edge cases
test-data-factory	FieldSchema → typed fixture factory for tests/stories
fix-failing-tests	Run the suite, classify failures by root cause, generate targeted fixes
legacy-analyzer	22-tool health audit for any React/Next.js/Remix app — scores 0–100, migration hints

Monorepo & Infrastructure

Tool	What it does
dep-auditor	Unused deps, duplicate versions, circular imports, bundle impact analysis
monorepo-manager	Workspace listing, dependency graph, health check, shared dep finder
lighthouse-runner	Static HTML audit — meta tags, a11y, OG/Twitter cards, canonical, JSON-LD
json-viewer	Interactive HTML JSON viewer — collapsible, searchable, dark/light

CRUD Factory

One JSON API sample (or OpenAPI schema) fans out into a full, typed CRUD feature. Every generator keys off the shared FieldSchema contract, so the pieces compose.

Tool	What it does
infer-fields	JSON sample / OpenAPI → typed FieldSchema (types, FK relations, table/form defaults)
zod-schema-generator	FieldSchema → Zod schema + inferred TS type
api-client-generator	FieldSchema → RTK Query slice or TanStack Query hooks, with cache tags
form-generator	FieldSchema → React Hook Form + Zod form (create / edit)
table-generator	FieldSchema → TanStack Table (sort / filter / paginate)
detail-generator	FieldSchema → typed detail view + delete action
crud-composer	Wire the pieces into routes — React Router 7 or Next App Router
form-wizard-generator	FieldSchema → multi-step RHF+Zod wizard with per-step validation
msw-mock-generator	FieldSchema → MSW handlers + seed data, so the feature runs against a mock API
workflow-runner	Runs the whole chain end-to-end, gated by review-gate — files + journal + A–F grade
e2e-generator	FieldSchema → Playwright CRUD flow spec (create→edit→delete + a11y)
playwright-scaffolder	Scaffold the Playwright harness — config, fixtures, base POM, auth setup
visual-regression-setup	Playwright toHaveScreenshot specs for routes/stories — catch CSS drift

CRA → Vite

Migrate a Create React App project to Vite: analyze → plan → scaffold → migrate → verify.

Tool	What it does
cra-to-vite	Orchestrator — runs the six tools below in sequence, one call, graded report
craconfig-analyzer	Deep CRA config inspection (react-scripts, env, proxy, jest, browserslist, SVG)
dependency-remapper	CRA deps → Vite plan (remove/add with versions + unmapped)
env-var-migrator	REACT_APP_* → import.meta.env.VITE_*, in source and .env files
jest-to-vitest-migrator	jest.* → vi.*, adds the right imports, flags manual-review cases
vite-project-scaffolder	Generates vite.config.ts, main.tsx, strict tsconfig, a Vitest block
webpack-config-translator	Best-effort webpack/CRACO → Vite translation + manual-review list

Boilerplate

Tool	What it does
barrel-generator	Generate an index.ts barrel re-exporting a folder — no drifting export lists
type-from-json	JSON sample → plain TS interfaces (nested objects become their own interfaces)
zustand-store-generator	State shape → typed Zustand store (setters, reset, persist/devtools)
svg-to-component	Raw SVG → typed React component (SVGProps, currentColor) — SVGR-grade
env-config-generator	Zod-validated typed env module (Vite/Next) — fail fast on missing/bad vars
states-scaffolder	Loading/empty/error state components + a switch wrapper for a data view

Meta

Tool	What it does
mcp-tool-factory	Scaffold + wire + verify new MCP tools in this package
mcp-tool-improviser	Analyze + improve MCP tools across 7 dimensions — proposed diffs, apply, rollback
docs-generator	Generate a README (from an MCP tool) or an API reference (from a TS module + JSDoc)

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Automation workflows

Chain tools together for common tasks:

Workflow	Chain
Code Modernization	legacy-analyzer → code-modernizer → typescript-enforcer → generate-tests
Component Quality Pipeline	component-factory → component-reviewer → accessibility-checker → storybook-generator
Render Performance Audit	render-analyzer → performance-audit → quality-pipeline
App Health Check	legacy-analyzer → component-reviewer → generate-tests
Dependency Health	dep-auditor [unused → duplicates → bundle-impact] → monorepo-manager
Full CRUD feature	workflow-runner (composes the whole CRUD Factory chain in one call)
CRA → Vite migration	cra-to-vite (composes the whole CRA→Vite chain in one call)

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How MCP works

Claude Desktop / Cline / Cursor
        │  JSON-RPC over stdio
        ▼
   MCP Server (e.g. typescript-enforcer)
        │
        ▼
   Tool handlers (your code)

Each server extends McpServerBase from tools/shared/ — handles transport, routing, and error formatting. Adding a new tool is ~50 lines:

import { McpServerBase } from '@mcp-showcase/shared';

class MyTool extends McpServerBase {
  constructor() {
    super({ name: 'my-tool', version: '1.0.0' });
  }

  protected registerTools(): void {
    this.addTool('do_thing', 'Does a thing', {
      type: 'object',
      properties: { path: { type: 'string', description: 'Target path' } },
      required: ['path'],
    }, async (args) => {
      const { path } = args as { path: string };
      return this.success({ result: `Processed ${path}` });
    });
  }
}

new MyTool().run();

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Run from source (contributors)

Prefer npm for everyday use (see Install). Clone only to hack on the tools or run the showcase UI:

git clone https://github.com/Nishant-Chaudhary5338/mcp-toolkit.git
cd mcp-toolkit
npm install
npm run build
npm test          # run the full suite across all tools
npm run dev       # server on :3002, client on :5173

Point Claude Desktop at a local build the same way as Install, swapping npx -y mcp-react-toolkit <name> for node /path/to/mcp-toolkit/tools/<name>/build/index.js.

Use as a CLI / in CI

Every tool's build/index.js has a #!/usr/bin/env node shebang — pipe a JSON-RPC message to it on stdin:

# Health score + migration hints for a full app
echo '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"analyze-legacy-app","arguments":{"path":"/path/to/app"}}}' \
  | node tools/legacy-analyzer/build/index.js

# Review a component — grade A+ to F
echo '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"review","arguments":{"path":"src/components/Button.tsx"}}}' \
  | node tools/component-reviewer/build/index.js

# List a tool's available commands
echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | node tools/legacy-analyzer/build/index.js

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Testing

Every tool has a co-located Vitest suite covering its core logic directly — no MCP transport required.

npm test                              # all tools
npm run test -w tools/legacy-analyzer # single tool

CI runs on every push and PR against Node 20 and 22.

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Companion package

code-graph-indexer — indexes any TS/React/Next.js repo into a queryable code graph (files, components, functions, and the edges between them) and answers structural questions: who calls this, blast radius, dead code, semantic search. Same family, separate package.

npx code-graph-indexer ui --root .

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Contributing

See CONTRIBUTING.md — how to scaffold a new tool, write tests, and open a PR.

Stack

TypeScript strict · Node.js · MCP SDK 1.12 · Vitest · React 19 · Vite · Tailwind CSS · Express

Built by

Nishant Chaudhary — Senior Frontend Engineer · nishantchaudhary.dev@gmail.com

Also see: dashcraft · react-present · ai-builder

MIT License