MCP Workbench
Discover, validate, and test every MCP server across Cursor, VS Code, and Claude — in one place.
MCP server definitions end up scattered across half a dozen files with different root keys and transport conventions, and a single typo silently drops a server with no warning. MCP Workbench scans every known location, normalizes the results into one tree, and flags the misconfigurations that usually cost you an hour of debugging.
Features
- Unified discovery — one tree of every MCP server found across Cursor, VS Code, Claude Code, and Claude Desktop, grouped by source.
- Transport normalization —
stdio, http, and sse servers shown with a consistent shape regardless of which editor's field conventions the file used.
- Configuration validation — surfaces the silent failures: wrong root key, unparseable JSON,
npx without -y, and ${ENV} references that aren't set in your environment.
- Security & correctness checks — flags hardcoded API keys, credentials in URLs, plaintext
http:// remotes, unpinned npx/bunx launchers, curl | sh bootstrap chains, and cloud-metadata endpoints, all from the config you already have.
- Problems-panel diagnostics — every issue is published as a native VS Code diagnostic anchored to the exact key in the config file, so it shows up as a squiggle and in the Problems panel with click-to-jump.
- Connection testing — launch any server over the MCP SDK, run the
initialize handshake, and list its capabilities, tools, resources, and prompts (with input schemas) — or see the exact reason it failed to connect.
- Live tool calls, resource reads, and prompt fetches — fire a real
tools/call with arguments pre-filled from each tool's schema, read any resource (or fill in a template URI), and fetch a prompt's messages with its arguments — all against the live server, rendered inline.
- Provenance at a glance — every server shows which file and editor it came from, with the absolute config path one click away.
- Live refresh — re-scans automatically when any known MCP config changes in your workspace.
Screenshots
Hover any server to see its source, the exact config file it came from, and every validation issue:
Where it looks
| Source |
Location |
Root key |
| Cursor (global) |
~/.cursor/mcp.json |
mcpServers |
| Cursor (workspace) |
<workspace>/.cursor/mcp.json |
mcpServers |
| VS Code (workspace) |
<workspace>/.vscode/mcp.json |
servers |
| Claude Code (workspace) |
<workspace>/.mcp.json |
mcpServers |
| Claude Code (user) |
~/.claude.json |
mcpServers |
| Claude Desktop |
~/.claude/claude_desktop_config.json |
mcpServers |
Servers recorded per project under projects["<path>"].mcpServers in ~/.claude.json are scoped to the open workspace folder by default. Set mcpWorkbench.showAllClaudeProjects to list every recorded project. Edits to the global config files above refresh the tree automatically.
Validation checks
Every issue below is also published to the Problems panel, anchored to the exact key it concerns.
Configuration
| Issue |
Level |
What it catches |
missing-root-key |
error |
The right file with the wrong top-level key, so the editor loads no servers without warning. |
bad-json |
error |
A config file that can't be parsed. |
unknown-transport |
error |
An entry with neither a command (stdio) nor a url (http/sse). |
empty-command |
error |
An stdio server whose command is blank. |
empty-root-key |
warning |
The root key is present but defines no servers. |
npx-missing-y |
warning |
npx without -y/--yes, which can hang waiting for an install prompt. |
env-unset |
warning |
A ${VAR} / ${env:VAR} reference that isn't set in your environment. |
non-string-arg / non-string-value |
warning |
A non-string arg, env value, or header that would otherwise be silently coerced. |
Security
| Issue |
Level |
What it catches |
hardcoded-secret |
warning |
A literal API key or private key in an arg, env value, or header (OpenAI, Anthropic, GitHub, Slack, AWS, PEM). Use a ${VAR} reference instead. |
credential-in-url |
warning |
Credentials in the URL's userinfo or a token/secret/key-style query parameter, where they leak into logs. |
insecure-remote-transport |
warning |
A plaintext http:// URL to a non-local host, so traffic and credentials travel unencrypted. |
risky-shell-pipe |
warning |
An argument that pipes a downloaded script straight into a shell (curl … \| sh), running remote code at launch. |
encoded-powershell |
warning |
PowerShell invoked with an encoded command (-enc), which hides what actually runs. |
metadata-endpoint |
warning |
A URL pointing at the cloud metadata address (169.254.169.254), a common SSRF target. |
unpinned-launcher |
info |
npx/bunx/pnpm dlx/yarn dlx/npm exec running a package with no version pin, so a future release could change behavior. |
Turn the whole security lens off with mcpWorkbench.security.enabled: false, or retune individual rules with mcpWorkbench.security.ruleSeverity — e.g. { "unpinned-launcher": "off", "hardcoded-secret": "error" } (values: off, info, warning, error).
Install
Then click the MCP Workbench icon in the activity bar to open the Servers view.
Build from source
git clone https://github.com/wheelbarrel00/mcpworkbench.git
cd mcpworkbench
npm install
npm run compile
Press F5 to launch an Extension Development Host with MCP Workbench loaded, or run npm run package to build a .vsix you can install with --install-extension.
Usage
- Refresh — re-scan all locations from the view's title bar.
- Open Config File — right-click a server to jump to the exact file it came from.
- Test Server — click the ▶ button on a server (or right-click → Test Server) to connect over the MCP SDK and open a panel with the server's
initialize info, capabilities, tools, resources, and prompts — or the exact connection error. The panel stays connected while open: edit a tool's JSON arguments and click Call tool, Read a resource (filling in any template variables), or Get prompt with its arguments to run against the live server, then close the panel to disconnect.
Roadmap
- Opt-in support for VS Code user-profile
mcp.json paths.
License
MIT
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