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io.github.sebastienrousseau/noyalib-mcp

MCP server for lossless YAML 1.2 parsing, formatting, and validation (pure Rust).

Open source Open in the app JSON README (API)

About

MCP server for lossless YAML 1.2 parsing, formatting, and validation (pure Rust).

Details

Kind
MCP servers
Topic
No topic detected
Publisher
sebastienrousseau
Origin
official
Category
ferramentas
Transport
local
Version
0.0.41
Stars
1
Last push
2026-09-05T17:42:56Z
Repository state
ativo
Language
Rust
License
Apache-2.0
Added
2026-08-29 04:01:22
Updated
2026-09-08 14:01:33
Origin id
io.github.sebastienrousseau/noyalib-mcp

README

<!-- SPDX-License-Identifier: Apache-2.0 OR MIT -->

<p align="center">
  <img src="https://cloudcdn.pro/noyalib/v1/logos/noyalib.svg" alt="Noyalib logo" width="128" />
</p>

<h1 align="center">noyalib-mcp</h1>

<p align="center">
  <strong>Model Context Protocol server exposing noyalib's
  lossless YAML editing to AI agents (Claude Desktop, Claude
  Code, Cursor, Zed, Continue.dev, …).</strong>
</p>

<p align="center">
  <a href="https://github.com/sebastienrousseau/noyalib-mcp/actions"><img src="https://img.shields.io/github/actions/workflow/status/sebastienrousseau/noyalib-mcp/ci.yml?style=for-the-badge&logo=github" alt="Build" /></a>
  <a href="https://crates.io/crates/noyalib-mcp"><img src="https://img.shields.io/crates/v/noyalib-mcp.svg?style=for-the-badge&color=fc8d62&logo=rust" alt="Crates.io" /></a>
  <a href="https://docs.rs/noyalib-mcp"><img src="https://img.shields.io/badge/docs.rs-noyalib--mcp-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs" alt="Docs.rs" /></a>
  <a href="https://lib.rs/crates/noyalib-mcp"><img src="https://img.shields.io/badge/lib.rs-noyalib-orange.svg?style=for-the-badge" alt="lib.rs" /></a>
  <a href="https://scorecard.dev/viewer/?uri=github.com/sebastienrousseau/noyalib-mcp"><img src="https://img.shields.io/ossf-scorecard/github.com/sebastienrousseau/noyalib-mcp?style=for-the-badge&label=OpenSSF%20Scorecard&logo=openssf" alt="OpenSSF Scorecard" /></a>
</p>

---

## Contents

- [Install](#install) — Cargo, npx, Docker
- [Requirements](#requirements) — toolchain floor, platforms, the core pin
- [Quick Start](#quick-start) — JSON-RPC handshake
- [Why this approach?](#why-this-approach) — design rationale
- [Connect](#connect) — per-client configuration
- [Tools](#tools) — MCP tool reference
- [Examples](#examples) — runnable scripts
- [Verification](#verification) — cosign + npm provenance
- [When not to use noyalib-mcp](#when-not-to-use-noyalib-mcp)
- [Documentation](#documentation)
- [License](#license)

---

## Install

```bash
cargo install noyalib-mcp
```

For environments without a Rust toolchain (the typical AI-agent
deployment shape):

```bash
# npm wrapper — auto-downloads the matching binary on first run,
# caches under ~/.cache/noyalib-mcp/<version>/.
npx @sebastienrousseau/noyalib-mcp

# Container — multi-arch (linux/amd64, linux/arm64).
docker run --rm -i ghcr.io/sebastienrousseau/noyalib-mcp:latest
```

> **Split from the monorepo since v0.0.13.** Prior versions
> shipped from `sebastienrousseau/noyalib/crates/noyalib-mcp/`
> under the workspace-lockstep release cadence. From v0.0.13
> onward `noyalib-mcp` lives here as its own crate, still
> released in strict lockstep with the parent
> [`noyalib`](https://github.com/sebastienrousseau/noyalib) at
> the same version. See
> [ADR-0005](https://github.com/sebastienrousseau/noyalib/blob/main/docs/adr/0005-workspace-split.md)
> for the rationale and rollback recipe.

Both consume the same signed binary attached to every GitHub
Release. See [Verification](#verification) for the verify
commands.

---

## Requirements

- **Rust 1.86.0 or newer** to build from source: `rust-version` in
  the manifest, enforced by the `msrv-core` CI job on every push.
- **Any tier-1 platform.** CI runs the tests on Linux, macOS, and
  Windows with the stable, beta, and nightly toolchains; stable is the
  gate, beta and nightly are early warning.
- **The matching core.** This crate pins `noyalib` at the identical
  `=0.0.X` and releases in lockstep with it; Cargo resolves that pin
  for you.
- **An MCP client** speaking JSON-RPC 2.0 over stdio (2025-06-18 or
  2026-07-28 protocol eras); the README's Connect section lists tested
  hosts.

## Quick Start

The server speaks JSON-RPC 2.0 over stdio with newline-delimited
frames, per the
[MCP specification](https://modelcontextprotocol.io). A typical
agent launches the binary as a child process, sends
`initialize`, then dispatches tool calls:

```json
{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"agent","version":"0.0.1"}}}
{"jsonrpc":"2.0","method":"notifications/initialized"}
{"jsonrpc":"2.0","id":2,"method":"tools/list"}
{"jsonrpc":"2.0","id":3,"method":"tools/call",
 "params":{"name":"format","arguments":{"yaml":"a:1\nb:2\n"}}}
```

---

## Why this approach?

AI agents that edit YAML configuration today regex-replace and
corrupt comments, indentation, and document structure. The same
agent fixing a port number in a Kubernetes manifest can shift
every comment by a line, reorder sibling keys, or strip
trailing whitespace that a downstream linter cared about.

noyalib's CST does the edits losslessly — a `set("server.port",
"9090")` rewrites only the byte span of the `8080` scalar; the
surrounding comments and indentation pass through untouched.
This server is the protocol shim that lets MCP-aware clients
drive that engine safely:

- **Lossless mutation.** `tools/call set` returns a document
  byte-identical to the input outside the touched span.
- **Surgical reads.** `tools/call get` walks the dotted path
  and returns just the value, not the whole tree.
- **Schema validation.** `tools/call validate --schema` runs
  the same JSON Schema 2020-12 engine `noyavalidate` ships.
- **Stdio transport.** Standard MCP. Works with every
  spec-compliant client.

---

## Connect

### Claude Desktop / Claude Code

```bash
claude mcp add noyalib $(which noyalib-mcp)
```

### Cursor

`~/.cursor/mcp.json`:

```json
{
  "mcpServers": {
    "noyalib": {
      "command": "noyalib-mcp"
    }
  }
}
```

### Zed

`~/.config/zed/settings.json`:

```json
{
  "context_servers": {
    "noyalib": {
      "command": { "path": "noyalib-mcp" }
    }
  }
}
```

### Continue.dev

`~/.continue/config.json`:

```json
{
  "experimental": {
    "modelContextProtocolServers": [
      { "transport": { "type": "stdio", "command": "noyalib-mcp" } }
    ]
  }
}
```

### Any other MCP-aware client

Point at the binary; the transport is stdio with newline-
delimited JSON-RPC 2.0.

---

## Tools

The v0.0.1 server registers two file-oriented tools — both
operate on a YAML file at `file: <path>`, not on inline source
strings, so an agent's edits land on disk losslessly:

- `noyalib_get` — Takes `{ file: string, path: string }`; returns the raw source fragment at the dotted/indexed path (e.g. `server.host`, `items[0].name`). No re-quoting; no canonicalisation.
- `noyalib_set` — Takes `{ file: string, path: string, value: string }`; returns the file rewritten via the lossless CST so only the touched span changes; comments, blank lines, and sibling formatting survive byte-for-byte. The `value` is a YAML fragment (`0.0.2`, `"hello"`, `[1, 2, 3]`); a parse failure leaves the file unchanged.

Each tool's full input schema lives in the response to
`tools/list`. The server also handles the standard
`initialize` / `initialized` / `notifications/cancelled`
lifecycle.

Format / parse / validate are not exposed as MCP tools today —
they're available via the [`noya-cli`](../noya-cli/README.md)
binaries (`noyafmt`, `noyavalidate`) and the
[`noyalib`](../noyalib/README.md) library API. Promotion to
first-class MCP tools is on the v0.0.2+ roadmap.

---

## Examples

Agent-driving demos under
[`crates/noyalib-mcp/examples/`](examples/):

| Script | What it shows |
|---|---|
| [`handshake.sh`](examples/handshake.sh) | `initialize` → `tools/list` smoke test. Confirms the binary speaks the protocol and announces the expected tools. |
| [`format-call.sh`](examples/format-call.sh) | `tools/call format` on a poorly-spaced document. Demonstrates that comments + indentation pass through the CST formatter unchanged. |
| [`set-then-get.sh`](examples/set-then-get.sh) | Round-trip the mutation surface: `set` rewrites `server.port`, `get` reads it back. Surgical edit; surrounding bytes untouched. |

```bash
chmod +x crates/noyalib-mcp/examples/*.sh
crates/noyalib-mcp/examples/handshake.sh | jq -c .
```

POSIX-shell only — no `jq`, no `node` dependencies. Pipe
through `jq -c .` if you want pretty-printed JSON responses.

---

## Verification

GitHub Releases ship the crate archive and a CycloneDX SBOM,
each with a sigstore bundle and checksums; the GHCR image is
built from the tagged source. Pre-built binaries are not
attached to releases yet. To verify a release artefact:

```bash
COSIGN_EXPERIMENTAL=1 cosign verify-blob \
  --certificate-identity-regexp 'https://github.com/sebastienrousseau/noyalib-mcp/' \
  --certificate-oidc-issuer 'https://token.actions.githubusercontent.com' \
  --bundle <artefact>.bundle \
  <artefact>
```

The npm wrapper additionally carries an
[npm provenance attestation](https://docs.npmjs.com/generating-provenance-statements):

```bash
npm view noyalib-mcp provenance
```

Full cookbook: [`pkg/VERIFY.md`](https://github.com/sebastienrousseau/noyalib/blob/main/pkg/VERIFY.md).

---

## When not to use noyalib-mcp

- **You don't trust your AI agent with filesystem access at
  all.** noyalib-mcp doesn't read or write files itself —
  every operation takes the YAML document as a string argument
  and returns the result as a string. The agent decides what
  to do with the result. If the agent has filesystem access,
  it can persist the response wherever it wants.
- **You need a sandboxed schema registry.** noyalib-mcp accepts
  schemas as inline strings in `tools/call validate`; it does
  not fetch schemas from URLs. If your workflow needs
  network-resolved schemas, the agent is responsible for
  fetching the schema first and passing the bytes.

---

## Compatibility

**MSRV: Rust 1.86.0** stable — the lowest toolchain this crate
can be **built and tested** on, matching the `noyalib` core floor.
`criterion 0.8` (the benchmark dev-dependency) declares
`rust-version = 1.86`, so `cargo check --all-targets` and the
bench suite fail on 1.85 with `criterion@0.8.2 requires rustc
1.86` — `cargo check --lib` alone still builds on 1.85. We publish
the number we verify. The MCP wire surface itself is text-only
JSON-RPC and pulls no nightly-only deps. CI verifies the floor on every
PR via the `Per-crate MSRV` workflow job. The bump policy
lives in
[`docs/POLICIES.md`](https://github.com/sebastienrousseau/noyalib/blob/main/docs/POLICIES.md#1-msrv-minimum-supported-rust-version).

**Tier-1 platforms** (CI-verified each PR): `aarch64-apple-darwin`,
`x86_64-unknown-linux-gnu`, `x86_64-pc-windows-msvc`. The
binary writes via atomic file replacement on every platform —
on Windows via `MoveFileExW(MOVEFILE_REPLACE_EXISTING |
MOVEFILE_WRITE_THROUGH)` semantics.

---

## Documentation

The four entry points, identical across every repo in the family:

- **[User Manual](https://sebastienrousseau.github.io/noyalib-mcp/manual/)** — this crate's rendered book: its guides, architecture, and release notes; the family manual for the core library is at [https://sebastienrousseau.github.io/noyalib/manual/](https://sebastienrousseau.github.io/noyalib/manual/)
- **[API reference](https://docs.rs/noyalib-mcp)** — rustdoc on docs.rs
- **[Developer docs](DEVELOPMENT.md)** — this repo's dev entry point, pointing at the family guide
- **[Ecosystem map](https://github.com/sebastienrousseau/noyalib/blob/main/docs/ECOSYSTEM.md)** — the six crates, the lockstep model, the scorecard

- **Engineering policies** (MSRV, SemVer, security, performance, concurrency, platform support, feature flags):
  [`docs/POLICIES.md`](https://github.com/sebastienrousseau/noyalib/blob/main/docs/POLICIES.md)
- **Security policy**:
  [`SECURITY.md`](https://github.com/sebastienrousseau/noyalib/blob/main/SECURITY.md)
- **API reference**: <https://docs.rs/noyalib-mcp>
- **Tools reference (input schemas + error codes)**:
  [`docs/tools-reference.md`](docs/tools-reference.md)
- **Agent integration (Claude Desktop, Cursor, Continue.dev)**:
  [`docs/agent-integration.md`](docs/agent-integration.md)
- **MCP specification**: <https://modelcontextprotocol.io>
- **Workspace README**:
  <https://github.com/sebastienrousseau/noyalib#readme>

---

## Related MCP Servers

Sibling MCP servers by the same author — open-source, Apache-2.0 licensed, targeting banking and financial-services AI agents. `noyalib-mcp` complements them by giving agents lossless YAML editing for structured configuration files:

| Server | Purpose |
|---|---|
| [`pain001-mcp`](https://github.com/sebastienrousseau/pain001-mcp) | Generate & validate ISO 20022 pain.001 payment initiation files (Customer Credit Transfer) |
| [`bankstatementparser-mcp`](https://github.com/sebastienrousseau/bankstatementparser-mcp) | Parse bank statements (BAI2, MT940/MT942, CAMT.053, OFX, CSV) into structured transactions |
| [`camt053-mcp`](https://github.com/sebastienrousseau/camt053-mcp) | Parse & reconcile ISO 20022 camt.053 bank-to-customer statements — CBPR+/HVPS+ ready |
| [`acmt001-mcp`](https://github.com/sebastienrousseau/acmt001-mcp) | Generate & validate ISO 20022 acmt.001 account management messages |

---

## MCP Registry

`mcp-name: io.github.sebastienrousseau/noyalib-mcp`

---

## License

Dual-licensed under [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0)
or [MIT](https://opensource.org/licenses/MIT), at your option.

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