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MCP server.json validator & generator
Direct answer: paste your server.json to validate it field by field against the official MCP registry schema — version 2025-12-11, bundled into this page — with a plain-language fix for every problem. Or use the generator to build a valid file from a form, and the checklist to catch the non-schema failures that actually reject most first publishes. This validates the publisher manifest (server.json), not a client config (mcp.json) — paste the wrong file and the tool will tell you.
MCP server.json Validator & Generator
Schema problems
| Field | Rule | Problem | How to fix it |
|---|
Extra checks — guidance, not schema rules
Fill in what you have — the file is generated and re-validated as you type. Only include packages or remotes or both, as your server needs.
Packages (local installs)
Remotes (hosted endpoints)
Schema validity is necessary but not sufficient — most registry rejections and silent failures are one of these. Work through the list before you publish. This is guidance, not certification: the registry makes the final decision.
What the validator checks
Two clearly separated layers. Schema results come from running your file against the official JSON Schema itself: every failure is reported with its JSON path, the rule that failed (required field, type, pattern, URL format, …), and a concrete fix. Extra checks — labelled as guidance, never as schema failures — cover the things the schema permits but registries and clients trip on: a name outside the reverse-DNS convention, a file with neither packages nor remotes, an http:// repository URL.
The generator builds the document as you type and re-validates on every keystroke, so the file you download is valid against the same bundled schema — for every combination of packages, remotes, environment variables and headers the form can produce.
Frequently asked questions
Which schema version does this check against?
The official MCP server.json schema, version 2025-12-11. A copy of that exact schema is bundled into this page and the version is printed on it. When the schema is updated, this page is re-bundled and re-dated — until then it keeps naming 2025-12-11 rather than pretending to check "the latest".
Is this the same as validating mcp.json?
No — and confusing the two is the classic trap in this category. mcp.json is a client configuration: it tells an app which servers to run, and lives on the user's machine. server.json is the publisher manifest the official registry validates and lists. This page validates server.json; if you paste a client config, it detects the shape and tells you plainly instead of failing it against the wrong schema.
Is there a size cap on validation?
No artificial one. Some validators cap input at a few KB; server.json files are small by nature, and this validator handles any schema-sized file fully in the browser.
Does a "valid" result guarantee the registry will accept my server?
No. Schema validity is one gate; the registry also authenticates that you own the namespace in the name (for example the GitHub account behind io.github.…), checks that named packages exist, and makes the final decision itself. The pre-publish checklist covers the common non-schema failures.