Check MCP configuration JSON and a few broad structure mistakes in your browser before you paste it into a client. Choose the top-level format documented for your destination, paste the configuration, and review the local diagnostics. The page does not contact a server or upload the text.
Check a configuration
What does this checker validate?
It parses strict JSON, checks that the selected top-level key contains a non-empty object of server entries, checks that each entry is an object, and inspects common command, args, and url values when present. It does not enforce a complete client schema, launch a process, test a remote endpoint, verify credentials, or perform an MCP handshake. Comments and trailing commas are not valid JSON and will be reported by the parser.
The format selector only checks the documented root key for the selected VS Code or portable Copilot format. Other fields differ by client and destination, including transport names, supported options, and authentication. Choose the destination’s current documentation before relying on a passing check.
Why can one MCP configuration fail in another client?
Configuration shape is client-specific. Current VS Code documentation distinguishes its servers format from portable Copilot mcpServers files and notes that other providers can use different locations and schemas. A public MCP server issue also records a user report of a JSON syntax mistake causing a Desktop configuration not to load; it is an individual troubleshooting report, not prevalence evidence. JSON validity is only the first check—confirm the exact destination schema and test the connection in that client.
What should I check before enabling a server?
- Confirm the configuration file path and root key for your exact client and workflow.
- Review the command, package source, arguments, URL, and environment values before starting the server.
- Keep credentials out of shared files when the client offers a documented secret or environment-variable mechanism.
- Check what tools the server exposes and what permissions the client grants them.
- Start or connect through the client and verify a harmless expected tool call; this page cannot test runtime behavior.
Frequently asked questions
Does a passing result mean the configuration works?
No. It confirms strict JSON syntax and limited broad structure checks. It does not validate every client-specific property, start a server, test network access or authentication, or verify the MCP protocol handshake.
Can I paste a VS Code file into Copilot portable configuration?
Check the destination first. Current VS Code documentation describes a VS Code format with a top-level servers key and portable Copilot files with a top-level mcpServers key. It also documents differences in supported fields and variable syntax.
Is my pasted configuration sent anywhere?
No. Parsing and formatting run in this page’s browser. Do not paste live credentials into any web form; use placeholders while reviewing configuration structure.
What evidence supports this tool?
First-party Visual Studio Code and GitHub documentation describe multiple MCP configuration formats. A public MCP server issue provides one qualitative example of a JSON syntax problem in client setup. None of these sources measures how common configuration failures are.
Sources · checked November 3, 2026
- Visual Studio Code: MCP servers · setup and configuration overview
- Visual Studio Code: MCP configuration reference · documented root keys and format differences
- GitHub Docs: Configure MCP servers for your repository · Copilot mcpServers format
- MCP servers issue #3460 · individual report involving MCP client configuration and JSON syntax
Related: MCP client setup documentation, Claude Code MCP proxy troubleshooting, and coding assistants.
Methodology and limitations
The browser-only helper uses strict JSON parsing and limited structural checks. For selected VS Code and portable Copilot formats it checks the documented top-level key; broad checks inspect object entries and common command, args, and URL values. It does not validate a complete client schema, start a process, or test a connection. Official VS Code and GitHub documentation and the linked qualitative configuration report were checked November 3, 2026.
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