Encode and decode HTML entities, URL-encoding, and Unicode escapes via @mukundakatta/encoding-mcp (npx)

Recipe: Encode/decode HTML entities, URL-encoding, and Unicode escapes

Server: @mukundakatta/encoding-mcp v0.1.0 Transport: stdio via npx @mukundakatta/encoding-mcp Auth: none required Tools: 1 — transform Schema: { text: string, flavor: "html" | "url" | "unicode", op: "encode" | "decode" } (all required)

What it does

Single tool with three encoding flavors:

• html — <, &, ", &#NNN; etc. Essential for XSS prevention and HTML parsing.
• url — %20, %26, %3D etc. Standard percent-encoding for URL components.
• unicode — \uXXXX JavaScript escape sequences, including surrogate pairs for emoji.

Verified trace (6 calls, 100% success)

HTML encode (XSS sanitization):

→ tools/call { name: "transform", arguments: { op: "encode", flavor: "html", text: "<script>alert(\"XSS & injection\")</script>" } }
← { result: "&lt;script&gt;alert(&quot;XSS &amp; injection&quot;)&lt;/script&gt;" }

HTML decode:

→ tools/call { name: "transform", arguments: { op: "decode", flavor: "html", text: "<div>Hello & welcome</div>" } }
← { result: "<div>Hello & welcome</div>" }

URL encode:

→ tools/call { name: "transform", arguments: { op: "encode", flavor: "url", text: "hello world & foo=bar?q=1+2" } }
← { result: "hello%20world%20%26%20foo%3Dbar%3Fq%3D1%2B2" }

URL decode (roundtrip):

→ tools/call { name: "transform", arguments: { op: "decode", flavor: "url", text: "hello%20world%20%26%20foo%3Dbar%3Fq%3D1%2B2" } }
← { result: "hello world & foo=bar?q=1+2" }

Unicode encode (emoji → surrogate pairs):

→ tools/call { name: "transform", arguments: { op: "encode", flavor: "unicode", text: "café ☕ 😀" } }
← { result: "caf\\u00e9 \\u2615 \\ud83d\\ude00" }

Unicode decode:

→ tools/call { name: "transform", arguments: { op: "decode", flavor: "unicode", text: "caf\\u00e9 \\u2615 \\ud83d\\ude00" } }
← { result: "café ☕ 😀" }

Gotcha

On macOS, /tmp symlinks to /private/tmp. If you install via npm install --prefix /tmp/... and run via node path/to/server.js, the server's import.meta.url resolves to /private/tmp/... while process.argv[1] gets /tmp/..., causing the entry-point guard to fail silently (process exits 0, no error, no output). Fix: resolve the real path with realpath before passing to node, or use the MCP SDK's StdioClientTransport which handles this.

Claude Code config

{ "mcpServers": { "encoding": { "command": "npx", "args": ["-y", "@mukundakatta/encoding-mcp"] } } }