MCP Validator Function

Overview

This directory contains the Azure Function that implements the Model Context Protocol (MCP) server for validating oh-my-posh configurations.

Endpoints

• POST /api/mcp - MCP server endpoint that handles validation requests
• GET /api/mcp - Returns server information and available tools

Supported Tools

validate_config

Validate an oh-my-posh configuration.

• Supports JSON, YAML, and TOML formats
• Returns detailed validation errors with JSON paths

validate_segment

Validate a segment snippet (individual prompt segment).

• Validates against the segment schema definition
• Useful for testing individual segments before adding them to a full configuration
• Supports JSON, YAML, and TOML formats

Usage

As an MCP Server

Configure your MCP client to connect to this server:

{
  "mcpServers": {
    "oh-my-posh-validator": {
      "url": "https://ohmyposh.dev/api/mcp",
      "transport": "http"
    }
  }
}

Direct HTTP Requests

Get Server Info

curl https://ohmyposh.dev/api/mcp

List Available Tools

curl -X POST https://ohmyposh.dev/api/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/list",
    "id": 1
  }'

Validate a Configuration

curl -X POST https://ohmyposh.dev/api/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "validate_config",
      "arguments": {
        "content": "{\"$schema\":\"https://raw.githubusercontent.com/JanDeDobbeleer/oh-my-posh/main/
themes/schema.json\",\"blocks\":[]}",
        "format": "json"
      }
    },
    "id": 1
  }'

Validate a Segment Snippet

curl -X POST https://ohmyposh.dev/api/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "validate_segment",
      "arguments": {
        "content": "{\"type\":\"path\",\"style\":\"powerline\",\"foreground\":\"#ffffff\",\"background\":\"#61AFEF\",\"template\":\" {{ .Path }} \"}",
        "format": "json"
      }
    },
    "id": 2
  }'

Response Format

The validation result includes:

• valid: Boolean indicating if the configuration is valid
• errors: Array of validation errors (if any)
• warnings: Array of warnings (best practices, deprecations)
• detectedFormat: The detected or specified format
• parsedConfig: The parsed configuration object (for debugging)

Example response:

{
  "jsonrpc": "2.0",
  "result": {
    "content": [
      {
        "type": "text",
        "text": "{
          \"valid\": true,
          \"errors\": [],
          \"warnings\": [
            {
              \"path\": \"$schema\",
              \"message\": \"Consider adding \\\"$schema\\\" property for better editor support.\",
              \"type\": \"recommendation\"
            }
          ],
          \"detectedFormat\": \"json\",
          \"parsedConfig\": {...}
        }"
      }
    ]
  },
  "id": 1
}

Development

To test locally:

cd website/api
npm install
npm start

Then send requests to http://localhost:7071/api/mcp

Publishing to MCP Registry

This server is published to the MCP Registry using GitHub Actions.

Publishing

Publishing is triggered automatically when you push a version tag (same as oh-my-posh releases):

git tag v9.0.0
git push origin v9.0.0

The workflow will:

1. Extract version from the tag (e.g., v9.0.0 → 9.0.0)
2. Update server.json version to match
3. Validate the server.json file
4. Authenticate with the MCP Registry using GitHub OIDC
5. Publish the server to the registry

Note: The MCP server version will stay in sync with oh-my-posh versions automatically.

Files

• server.json - MCP Registry server configuration
• server.schema.json - JSON schema for validation
• validate-server.js - Validation script
• .github/workflows/publish-mcp.yml - GitHub Actions workflow

Validating server.json Locally

cd website/api
npm install
cd mcp
node validate-server.js