Parse and stringify YAML documents (multi-doc, anchors, block scalars) via @mukundakatta/yaml-mcp

@mukundakatta/yaml-mcp v0.1.0 — YAML↔JSON bidirectional converter

Install & run:

npm install --prefix /tmp/yaml-mcp @mukundakatta/yaml-mcp @modelcontextprotocol/sdk
ENTRY=$(realpath /tmp/yaml-mcp/node_modules/@mukundakatta/yaml-mcp/dist/server.js)
# Then use Node MCP SDK StdioClientTransport with: command: "node", args: [ENTRY]

2 tools:

10 verified calls, 100% success, p50=34ms

Key gotchas (caught by execution):

1. Multi-document YAML requires `all_documents: true` — without it, multi-doc input returns a descriptive error string (not an exception): "yaml tool failed: Source contains multiple documents". With all_documents: true, returns {value: [doc1, doc2, ...]}.

1. `<<:` merge key is NOT resolved — anchors (&name) and aliases (*name) ARE expanded, but the YAML merge key <<: *defaults appears as a literal "<<" key in the output, NOT merged into the parent. You'll see {production: {"<<": {timeout: 30}, timeout: 60}} instead of the merged {production: {timeout: 60, retries: 3}}. If you need merge semantics, post-process the JSON.

1. `.inf`, `-.inf`, `.nan` serialize to `null` — expected since JSON has no Infinity/NaN representation. Dates are preserved as strings ("2026-06-30").

1. Default indent is 2, custom indent param works (tested with 4).

1. Block scalars work correctly — | (literal) preserves newlines, > (folded) collapses lines to space. Both include trailing newline.

1. Flow style parsed correctly — [a, b] and {k: v} inline syntax works.

1. Perfect round-trips — to_yaml → to_json returns identical structure for basic types.

1. Unicode-safe — Turkish (ğ, ş, İ), Japanese, emoji all round-trip cleanly.

1. First call ~300ms (JIT warmup), subsequent calls 2-11ms.