Free browser utility
All toolsMCP config checker
Choose your client and exact file format, then check the core shape of an MCP configuration. Use placeholder credentials: real credentials are unnecessary. This utility checks in your browser without uploading your input; it does not connect to a server or run a command.
This utility generates in your browser without uploading input. No signup or AI provider is needed. Use non-secret project context.
MCP configuration report
Start with the example or enter your own facts. Use Check MCP config when you are ready, then review the result.
Methodology and format
The checker parses strict JSON with the browser's native JSON parser, then walks it iteratively before inspecting core fields. Limits are 150,000 JavaScript string characters, 20 servers, 100 entries per array or object, 16 levels below the root, and 10,000 JSON values. These are utility limits, not claims about client limits.
Claude Code project .mcp.json and Cursor .cursor/mcp.json use mcpServers. The VS Code choice here is specifically .vscode/mcp.json with servers. VS Code also supports a portable .mcp.json format with mcpServers, which this checker does not assess under the VS Code choice. Confirm the file format before interpreting a root-field issue.
The supported core is stdio command, string args and env mappings, plus HTTP/SSE url, type and string headers. VS Code env values may also be numbers or null. Stdio is inferred when command is present and type is absent; for Cursor and VS Code, a scope note explains the documentation's explicit-type table and type-free examples. Cursor's URL example permits remote entries without type; this check requires a remote type for the Claude Code and VS Code choices.
A report separates core shape issues from unchecked features. It identifies known field paths with numbered server entries instead of names. Server and map entry numbers follow parsed object order, starting at 1; argument indexes start at 0. No configuration values or arbitrary key names appear in the report. Copy and Markdown export include only this report.
The example combines a fictional local notes command and an example.com HTTP endpoint. It demonstrates shape only. Replace the example with your own non-secret configuration, check it explicitly, and review the result alongside the official documentation. Editing either field clears the previous report until you check again.
Claude Code MCP documentation — Project configuration, transports and environment variable expansion.
Cursor MCP documentation — mcp.json examples, stdio fields, remote configuration and interpolation.
VS Code MCP configuration reference — Both root formats, core field types, environment values and HTTP/SSE configuration.
Limitations
This is a static supported-core shape check, not proof of full client acceptance, installation, a trusted executable, connectivity, endpoint availability, authentication or permissions. A report without issues does not establish a working MCP connection.
JSONC is outside this tool's parser even when a client accepts it. Duplicate JSON keys are not detected: native parsing keeps the last value. Use unique keys before checking. Unknown optional fields are explicitly unchecked rather than declared invalid. OAuth, helpers, envFile, cwd, input definitions and sandbox settings are outside the checked core.
Variable references are not expanded or validated. URLs containing variable syntax are left unchecked. Other transports, including WebSocket, and VS Code socket or named-pipe URLs are outside the HTTP URL checks. Recognizing legacy SSE shape does not imply that AppHandoff or a particular endpoint offers SSE.
The utility neither persists nor logs raw configuration and offers no raw-config share link. Use placeholders instead of secrets. These statements describe this utility's input handling, not all website requests or scripts. Official client formats can change; the sources below were reviewed on October 9, 2026.
Frequently asked questions
Does valid JSON mean my MCP config will connect?
No. JSON parsing only establishes syntax. This checker then checks selected core fields for the chosen format. It never launches a command, contacts an endpoint or verifies authentication, permissions or full client acceptance.
Which VS Code MCP configuration format does this check?
The VS Code choice checks .vscode/mcp.json with a servers root. VS Code also supports portable .mcp.json with mcpServers; that portable format is outside this choice. A root-field issue may mean you selected the wrong file format.
Can I paste JSONC or environment variable references?
This checker accepts strict JSON only, so comments and trailing commas produce a parser limitation message even when your client accepts JSONC. Variable references may remain in strings, but their syntax, resolved values and referenced resources are unchecked.
What happens to credentials in my configuration?
Use placeholders; real credentials are unnecessary. Checking runs in your browser without uploading input. This utility does not save or log raw configuration and cannot create a raw-config share link. Reports withhold server names, arbitrary key names and all configuration values. Copy and export happen only when requested.
Why are some fields marked unchecked?
The checker covers a bounded core of stdio and HTTP/SSE settings. Optional client fields, other transports and variable resolution need the client's own documentation and runtime. Unchecked does not mean invalid; it means this tool cannot establish acceptance of that part.
Related guides and tools
Diagnose a live connection with MCP Inspector
Understand MCP and its client-server boundary