Convert XML↔JSON bidirectionally via @mukundakatta/xml-mcp (npx)

Recipe: Convert XML↔JSON via @mukundakatta/xml-mcp

Surface: @mukundakatta/xml-mcp v0.1.0 (npm) Transport: stdio (NDJSON) Launch: npx -y @mukundakatta/xml-mcp Tools: 2 — to_json, to_xml Backed by: fast-xml-parser

Tool schemas

[
  {
    "name": "to_json",
    "description": "Parse XML and return a JSON-compatible value. Attributes are prefixed with @_.",
    "inputSchema": { "type": "object", "properties": { "xml": { "type": "string" } }, "required": ["xml"] }
  },
  {
    "name": "to_xml",
    "description": "Serialize a JSON object back to XML. Keys starting with @_ become attributes.",
    "inputSchema": { "type": "object", "properties": { "value": { "type": "object" } }, "required": ["value"] }
  }
]

Verified trace 1: XML → JSON

Request:

{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"to_json","arguments":{"xml":"<bookstore><book category=\"fiction\"><title lang=\"en\">Dune</title><author>Frank Herbert</author><year>1965</year><price>12.99</price></book><book category=\"science\"><title lang=\"en\">A Brief History of Time</title><author>Stephen Hawking</author><year>1988</year><price>15.50</price></book></bookstore>"}}}

Response (6ms):

{
  "value": {
    "bookstore": {
      "book": [
        {
          "title": { "#text": "Dune", "@_lang": "en" },
          "author": "Frank Herbert",
          "year": 1965,
          "price": 12.99,
          "@_category": "fiction"
        },
        {
          "title": { "#text": "A Brief History of Time", "@_lang": "en" },
          "author": "Stephen Hawking",
          "year": 1988,
          "price": 15.5,
          "@_category": "science"
        }
      ]
    }
  }
}

Verified trace 2: JSON → XML

Request:

{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"to_xml","arguments":{"value":{"config":{"@_version":"1.0","database":{"host":"localhost","port":5432,"name":"mydb"},"cache":{"@_enabled":"true","ttl":3600}}}}}}

Response (4ms):

<config version="1.0">
  <database>
    <host>localhost</host>
    <port>5432</port>
    <name>mydb</name>
  </database>
  <cache enabled>
    <ttl>3600</ttl>
  </cache>
</config>

Attribute convention

• XML attributes map to JSON keys prefixed with @_ (e.g. category="fiction" → "@_category": "fiction")
• Text content in mixed elements uses #text key
• Numeric values are auto-parsed from XML strings

⚠️ macOS caveat

On macOS, /tmp is a symlink to /private/tmp. The server's import.meta.url === file://${process.argv[1]} guard fails if you invoke via a /tmp path. Use the real path (/private/tmp/...) or invoke via npx (which resolves correctly).

Performance

• Cold start: ~100ms
• Tool call latency: ~4–6ms (in-process, no network)
• Handles deeply nested XML, multiple root children auto-wrapped in arrays