MCP Server Validator — Free Developer & Technical Tools

MCP Server Validator

Validate your Model Context Protocol manifest — required fields, tool schemas, description quality

Model Context Protocol (MCP) is Anthropic's 2024 standard for connecting LLMs to tools and data sources. Paste your server manifest (the JSON returned by initialize) below.

MCP manifest JSON

Errors

Warnings

Passing

tools[1].inputSchema.properties.path

Each property should have a 'description' — LLMs rely on these to fill arguments correctly.

คุณอาจจะชอบ

Base64 Encoder/Decoder

Encode and decode Base64 strings

JSON Formatter

Format and validate JSON data

Hash Generator

Generate MD5, SHA1, SHA256 hashes

About the MCP Server Validator

The Model Context Protocol (MCP) is Anthropic's 2024 open standard for connecting LLMs to tools and data sources. Its ecosystem is growing fast — Claude Desktop, Zed, Continue, and more. Getting the manifest right matters because the descriptions you write directly shape whether the LLM calls your tools correctly. This validator catches structural and quality issues before you ship.

Features

Validates required top-level fields (name, version, protocolVersion, capabilities)

Checks every tool has name, description, inputSchema

Warns on vague descriptions (LLMs choose tools by description — bad ones = wrong tool calls)

Validates inputSchema is proper JSON Schema with type: object

Flags missing property descriptions

Resource and prompt validation

How it works

Paste your MCP server manifest JSON (the response from initialize or your server.json).

Review errors (must-fix) and warnings (should-fix).

Iterate until all checks pass.

Use cases

MCP server development

Anthropic tool-use QA

Claude Desktop extensions

Pre-release validation

Agent debugging

Frequently asked questions

What is MCP?

Model Context Protocol, introduced by Anthropic in Nov 2024. It's an open standard for connecting LLMs to data sources and tools — think USB-C for AI. Claude Desktop, Zed, and several other clients support it.

Why does description quality matter so much?

The LLM chooses which tool to call based on the description. Vague descriptions like 'do stuff' lead to wrong tool selection. Clear ones like 'Fetches the current weather for a given city; use when the user asks about weather, temperature, or conditions' dramatically improve accuracy.

Is this the MCP spec as of 2024-11-05 or 2025-03-26?

Validation covers both protocol versions. We warn if you're on the older 2024-11-05 version — upgrading is usually easy and adds useful features.

Can I test the server runtime, not just the manifest?

This validates the static manifest only. Runtime testing (initialize → list_tools → call) requires a running server — use the MCP Inspector from modelcontextprotocol.io for that.

Does it validate JSON-RPC message schemas?

Not yet. Manifest validation only.