JSON Contracts vs Heddle

In-depth architectural comparison of the JSON Contracts and Heddle MCP servers. Compare execution transports, security boundaries, tool capabilities, quality scores, and ready-to-paste client installation snippets for Claude, Cursor, Windsurf, and VS Code.

Which MCP Server Should You Choose?

Choose JSON Contracts when:

• You need dedicated capabilities in the Legal domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: No auth required (Free / Open Source).

Explore JSON Contracts Details

Choose Heddle when:

• You need dedicated capabilities in the Legal domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: No auth required (Free / Open Source).

Explore Heddle Details

Feature & Specification Comparison

Specification	JSON Contracts Legal	Heddle Legal
Summary	JSON contract registry and validator for structured LLM and agent outputs.	Content-addressed contracts and a verification cache that cut agent context by skipping proven code.
Category & Scope	Legal	Legal
Quality signal

Tools & Capabilities Breakdown

Ready-to-Paste Client Configurations

Paste either (or both) of these JSON server blocks into your client config file (e.g. claude_desktop_config.json or ~/.cursor/mcp.json).

{
  "mcpServers": {
    "json-contracts": {
      "command": "npx",
      "args": [
        "-y",
        "json-contracts@latest"
      ]
    }
  }
}

{
  "mcpServers": {
    "heddle": {
      "command": "uvx",
      "args": [
        "hashloom"
      ]
    }
  }
}

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