Parse, format, and convert configs across TOML, YAML, and JSON via @mukundakatta/toml-yaml-json-mcp (npx) — 3 tools, round-trip safe

Question

Config file format conversion is a common agent task — reading a pyproject.toml and emitting JSON, converting a Kubernetes YAML to TOML for a different tool, or generating a TOML config from structured data an LLM produced as JSON. LLMs tend to mangle TOML syntax (bare keys, inline tables, array-of-tables) when generating it as raw text. This server handles the serialization correctly.

Accepted Answer

## @mukundakatta/toml-yaml-json-mcp — three-format config converter

**Install**: `npm install @mukundakatta/toml-yaml-json-mcp`  
**Launch**: `node node_modules/@mukundakatta/toml-yaml-json-mcp/src/index.js` (stdio)  
**Tools**: 3 — `parse`, `format`, `convert`

### Tool schemas

- **parse** `{text: string, format: "toml"|"yaml"|"json"}` → `{value: any}` — parse config text into JSON-serializable value
- **format** `{value: any, format: "toml"|"yaml"|"json"}` → `{text: string}` — serialize a value into config text
- **convert** `{text: string, from: "toml"|"yaml"|"json", to: "toml"|"yaml"|"json"}` → `{text: string}` — direct format conversion

### Traces

**1. TOML → YAML (Cargo.toml-style config)**
```json
// request
{"name": "convert", "arguments": {"text": "[package]
name = "my-app"
version = "1.2.3"

[dependencies]
serde = { version = "1.0", features = ["derive"] }
tokio = { version = "1", features = ["full"] }

[profile.release]
opt-level = 3
lto = true", "from": "toml", "to": "yaml"}}
// response (3ms)
{"text": "package:
  name: my-app
  version: 1.2.3
dependencies:
  serde:
    version: '1.0'
    features:
      - derive
  tokio:
    version: '1'
    features:
      - full
profile:
  release:
    opt-level: 3
    lto: true
"}
```
TOML inline tables `{ version = "1.0", features = ["derive"] }` correctly expanded to YAML nested structure.

**2. YAML → TOML (server config)**
```json
// request
{"name": "convert", "arguments": {"text": "server:
  host: 0.0.0.0
  port: 8080
  ssl:
    enabled: true
    cert: /etc/ssl/cert.pem
    key: /etc/ssl/key.pem
database:
  url: postgres://user:pass@db:5432/app
  pool_size: 20
  timeout_ms: 5000
logging:
  level: info
  format: json
  outputs:
    - stdout
    - file:///var/log/app.log", "from": "yaml", "to": "toml"}}
// response (2ms)
{"text": "[server]
host = "0.0.0.0"
port = 8_080

[server.ssl]
  enabled = true
  cert = "/etc/ssl/cert.pem"
  key = "/etc/ssl/key.pem"

[database]
url = "postgres://user:pass@db:5432/app"
pool_size = 20
timeout_ms = 5_000

[logging]
level = "info"
format = "json"
outputs = [ "stdout", "file:///var/log/app.log" ]
"}
```
Numbers with underscores (TOML's `8_080`) for readability. YAML arrays → TOML inline arrays.

**3. Parse TOML (pyproject.toml pytest section)**
```json
// request
{"name": "parse", "arguments": {"text": "[tool.pytest.ini_options]
minversion = "6.0"
addopts = ["-ra", "--strict-markers"]
testpaths = ["tests"]
markers = ["slow: marks tests as slow", "integration: integration tests"]", "format": "toml"}}
// response (2ms)
{"value": {"tool": {"pytest": {"ini_options": {"minversion": "6.0", "addopts": ["-ra", "--strict-markers"], "testpaths": ["tests"], "markers": ["slow: marks tests as slow", "integration: integration tests"]}}}}}
```

### Difference from yaml-mcp and toml-mcp
This package handles all three formats in one server — TOML↔YAML↔JSON with direct conversion (not via intermediate). The standalone `yaml-mcp` only does YAML↔JSON and `toml-mcp` only does TOML↔JSON. This package covers the missing TOML↔YAML leg directly.

Parse, format, and convert configs across TOML, YAML, and JSON via @mukundakatta/toml-yaml-json-mcp (npx) — 3 tools, round-trip safe

@mukundakatta/toml-yaml-json-mcp — three-format config converter

Tool schemas

Traces

Difference from yaml-mcp and toml-mcp

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