JSON Schema Validator Connector for AI agents.

Q: Can I use this to prevent hallucinations?

Yes. By using validatefunctioncall, you can detect when an LLM attempts to use parameters that do not exist in your schema, allowing you to catch hallucinations before they reach your downstream logic.

Q: What format should the input be in?

The payloadJson and schemaJson must both be provided as valid JSON strings.

1 live capability

Stop LLM hallucinations from breaking your function calling workflows.

Live agent request JSON Schema Validator / Connector

Waiting for input…

AI Agent

Why people use JSON Schema Validator

Stop LLM hallucinations with JSON Schema Function Call Validator

Instead of a clean execution, you get a cascade of 500 errors and broken database entries because the JSON was malformed.

What Vinkius changes

You stop broken function calls from crashing your downstream services.

Use it from Claude, ChatGPT, Cursor or another AI client you already have.

One account · 5,900+ Connectors

Real-world use case 01

Broken API calls in production

An agent tries to call a weather API but sends 'London' as an integer.
Real-world use case 02

Hallucinated parameters in complex schemas

Your agent adds a 'format' field that does not exist in your schema.
Real-world use case 03

Missing required fields in multi-step workflows

A developer needs all user IDs present in a batch update.

Complete set · 1capability

The complete JSON Schema Validator capability set.

These are the exact actions your AI can choose when you ask it to work with JSON Schema Validator.

Capability set01 / 01

01

1 capability in this set.

Part of 1 available through JSON Schema Validator.

01 Capability
Validate function call
Checks a JSON payload against your schema to find errors. It identifies missing, extra, or incorrectly typed parameters immediately.

Set up in minutes

One URL. Then ask JSON Schema Validator to work.

Claude and ChatGPT only need the Connector URL. Copy it once, add it in settings, and use JSON Schema Validator from the conversation.

Choose your client

Live preview

Advanced clients IDE · CLI

Claude · Web + desktop

Official guide ↗

Connector URL · ready to paste

Streamable HTTP

https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp

Step 01

Open Connectors

In Claude Web or Claude Desktop, open Settings and choose Connectors.
Step 02

Add the URL

Choose Add custom connector, name it JSON Schema Validator, and paste the URL above.
Step 03

Turn it on in chat

Select +, open Connectors, and enable JSON Schema Validator for the conversation.

ChatGPT · Web + desktop

Official guide ↗

Connector URL · ready to paste

Streamable HTTP

https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp

Step 01

Open MCP settings

On desktop, open Settings and MCP servers. On web, open your workspace app or connector settings.
Step 02

Add the URL

Choose Add server with Streamable HTTP, or create a custom MCP app, then paste the JSON Schema Validator URL.
Step 03

Save and start

Save the connection and enable JSON Schema Validator in your conversation. Desktop may ask you to restart once.

Cursor · IDE configuration

Official guide ↗

Advanced setup

{
  "mcpServers": {
    "json-schema-function-call-validator": {
      "url": "https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp"
    }
  }
}

Step 01

Open MCP Settings

Press Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows/Linux) → search "MCP Settings"
Step 02

Add the server config

Paste the JSON configuration above into the mcp.json file that opens
Step 03

Save the file

Cursor will automatically detect the new Connector
Step 04

Start using JSON Schema Validator

Open Agent mode in chat and ask: "Using JSON Schema Validator, help me...". 1 tools available

VS Code Copilot · IDE configuration

Official guide ↗

Advanced setup

{
  "mcpServers": {
    "json-schema-function-call-validator": {
      "url": "https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp"
    }
  }
}

Step 01

Create MCP config

Create a .vscode/mcp.json file in your project root
Step 02

Add the server config

Paste the JSON configuration above
Step 03

Enable Agent mode

Open GitHub Copilot Chat and switch to Agent mode using the dropdown
Step 04

Start using JSON Schema Validator

Ask Copilot: "Using JSON Schema Validator, help me...". 1 tools available

Windsurf · IDE configuration

Official guide ↗

Advanced setup

{
  "mcpServers": {
    "json-schema-function-call-validator": {
      "url": "https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp"
    }
  }
}

Step 01

Open MCP Settings

Go to Settings → MCP Configuration or press Cmd+Shift+P and search "MCP"
Step 02

Add the server

Paste the JSON configuration above into mcp_config.json
Step 03

Save and reload

Windsurf will detect the new server automatically
Step 04

Start using JSON Schema Validator

Open Cascade and ask: "Using JSON Schema Validator, help me...". 1 tools available

Cline · IDE configuration

Official guide ↗

Advanced setup

{
  "mcpServers": {
    "json-schema-function-call-validator": {
      "url": "https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp"
    }
  }
}

Step 01

Open Cline MCP Settings

Click the Connectors icon in the Cline sidebar panel
Step 02

Add remote server

Click "Add Connector" and paste the configuration above
Step 03

Enable the server

Toggle the server switch to ON
Step 04

Start using JSON Schema Validator

Ask Cline: "Using JSON Schema Validator, help me...". 1 tools available

Claude Code · Terminal command

Official guide ↗

Advanced setup

claude mcp add json-schema-function-call-validator --transport http "https://edge.vinkius.com/vk_preview_21yoFjCa6YURZm8sCCyeJadvPgEYlKfXVV7HUnII/mcp"

Step 01

Install Claude Code

Run npm install -g @anthropic-ai/claude-code if not already installed
Step 02

Add the Connector

Run the command above in your terminal
Step 03

Verify the connection

Run claude mcp to list connected servers, or type /mcp inside a session
Step 04

Start using JSON Schema Validator

Ask Claude: "Using JSON Schema Validator, show me...". 1 tools are ready

Build the capability set

Each Connector adds new actions and data without changing how you work.

Browse Connectors

01 3 capabilities

JSON Schema Strict Validator

Perform deterministic JSON validation against Draft-07 and 2020-12 schemas with strict property enforcement.

View Connector

02 3 capabilities New

JSON Schema Validator and Flattener

Strictly validate JSON against schemas and flatten nested structures using dot notation.

View Connector

03 1 capability

OpenAPI Validator Engine

Validate any OpenAPI or Swagger spec (2.0, 3.0, 3.1, 3.2) local before generating code from it. Returns version, validity, and every schema error with exact paths. Your spec quality gate.

View Connector

04 3 capabilities

Type Definition Consistency Checker

Ensure structural and type-level synchronization between TypeScript interfaces, Zod schemas, and Pydantic models.

View Connector

05 3 capabilities

JSON Schema Validator

Validate JSON documents and lint schemas for structural integrity.

View Connector

06 3 capabilities

JSON Payload Depth and Size Limiter

Validate JSON payloads against strict nesting depth and byte size constraints to prevent parser crashes.

View Connector

Bring your own AI

Change the model, client or framework. Keep JSON Schema Validator connected.

Claude
ChatGPT
Gemini
Cursor
VS Code
Windsurf
ZCode
Cline
Zed
Continue
Kiro
Roo Code
Zencoder
Goose
Void
Augment Code
Amp
Qodo
Tabnine
Pieces
Sourcegraph Cody
JetBrains
Warp
Amazon Q
Antigravity
BoltAI
Raycast
Jan
LM Studio
AnythingLLM
Open WebUI
Msty
Cherry Studio
LibreChat
TypingMind
Chorus
5ire
n8n
LangChain
LlamaIndex
CrewAI
Vercel AI SDK

Before you connect

Questions about JSON Schema Validator.

The practical details behind the request, access and result.

How can I prevent broken JSON in Claude?

Use this MCP to check every output against a schema. It catches errors before they break your downstream logic.

Does JSON Schema Function Call Validator detect extra fields?

Yes, it specifically flags any parameters that appear in the payload but are not defined in your provided schema.

Can I use this for debugging Cursor agent errors?

Absolutely. You can pass the outputs from your Cursor agent through this MCP to see exactly why a capability call is failing.

Will this MCP help with type mismatches in my agents?

Yes, it identifies when an agent sends a string where an integer or boolean is required by your schema.

How do I know if my agent is getting more reliable?

You can monitor the parameter validity percentage returned by the MCP to track improvements in your agent's accuracy over time.

What does the validator check for?

It checks for missing required parameters, type mismatches (like a string where an integer is expected), and hallucinated parameters that are not defined in your JSON Schema.

Can I use this to prevent hallucinations?

Yes. By using validate_function_call, you can detect when an LLM attempts to use parameters that do not exist in your schema, allowing you to catch hallucinations before they reach your downstream logic.

What format should the input be in?

The payloadJson and schemaJson must both be provided as valid JSON strings.

One connection away

Give your agent a direct line to JSON Schema Validator.

Connect JSON Schema Validator once. Keep it beside 5,900+ managed Connectors when the next task needs more.

Explore every Connector No credit card required · Free tier available

Stop LLM hallucinations with JSON Schema Function Call Validator

You stop broken function calls from crashing your downstream services.

Broken API calls in production

Hallucinated parameters in complex schemas

Missing required fields in multi-step workflows

Validate function call

Open Connectors

Add the URL

Turn it on in chat

Open MCP settings

Add the URL

Save and start

Open MCP Settings

Add the server config

Save the file

Start using JSON Schema Validator

Create MCP config

Add the server config

Enable Agent mode

Start using JSON Schema Validator

Open MCP Settings

Add the server

Save and reload

Start using JSON Schema Validator

Open Cline MCP Settings

Add remote server

Enable the server

Start using JSON Schema Validator

Install Claude Code

Add the Connector

Verify the connection

Start using JSON Schema Validator

JSON Schema Strict Validator

JSON Schema Validator and Flattener

OpenAPI Validator Engine

Type Definition Consistency Checker

JSON Schema Validator

JSON Payload Depth and Size Limiter

Give your agent a direct line to JSON Schema Validator.