registry/docs/modelcontextprotocol-io/package-types.mdx

---
title: MCP Registry Supported Package Types
sidebarTitle: Package Types
---

<Note>
  The MCP Registry is currently in preview. Breaking changes or data resets may occur before general availability. If you encounter any issues, please report them on [GitHub](https://github.com/modelcontextprotocol/registry/issues).
</Note>

# Package Types

The MCP Registry supports several different package types, and each package type has its own verification method.

## npm Packages

For npm packages, the MCP Registry currently supports the npm public registry (`https://registry.npmjs.org`) only.

npm packages use `"registryType": "npm"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/email-integration-mcp",
  "title": "Email Integration",
  "description": "Send emails and manage email accounts",
  "version": "1.0.0",
  "packages": [
    {
      "registryType": "npm",
      "identifier": "@username/email-integration-mcp",
      "version": "1.0.0",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

### Ownership Verification

The MCP Registry verifies ownership of npm packages by checking `mcpName` in `package.json`. The `mcpName` property **MUST** match the server name from `server.json`. For example:

```json package.json
{
  "name": "@username/email-integration-mcp",
  "version": "1.0.0",
  "mcpName": "io.github.username/email-integration-mcp"
}
```

## PyPI Packages

For PyPI packages, the MCP Registry currently supports the official PyPI registry (`https://pypi.org`) only.

PyPI packages use `"registryType": "pypi"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/database-query-mcp",
  "title": "Database Query",
  "description": "Execute SQL queries and manage database connections",
  "version": "1.0.0",
  "packages": [
    {
      "registryType": "pypi",
      "identifier": "database-query-mcp",
      "version": "1.0.0",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

### Ownership Verification

The MCP Registry verifies ownership of PyPI packages by checking for the existence of an `mcp-name: $SERVER_NAME` string in the package README (which becomes the package description on PyPI). The string may be hidden in a comment, but the `$SERVER_NAME` portion **MUST** match the server name from `server.json`. For example:

```markdown README.md highlight={5}
# Database Query MCP Server

This MCP server executes SQL queries and manages database connections.

<!-- mcp-name: io.github.username/database-query-mcp -->
```

## NuGet Packages

For NuGet packages, the MCP Registry currently supports the official NuGet registry (`https://api.nuget.org/v3/index.json`) only.

NuGet packages use `"registryType": "nuget"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/azure-devops-mcp",
  "title": "Azure DevOps",
  "description": "Manage Azure DevOps work items and pipelines",
  "version": "1.0.0",
  "packages": [
    {
      "registryType": "nuget",
      "identifier": "Username.AzureDevOpsMcp",
      "version": "1.0.0",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

### Ownership Verification

The MCP Registry verifies ownership of NuGet packages by checking for the existence of an `mcp-name: $SERVER_NAME` string in the package README. The string may be hidden in a comment, but the `$SERVER_NAME` portion **MUST** match the server name from `server.json`. For example:

```markdown README.md highlight={5}
# Azure DevOps MCP Server

This MCP server manages Azure DevOps work items and pipelines.

<!-- mcp-name: io.github.username/azure-devops-mcp -->
```

## Cargo (Rust) Packages

For Cargo packages, the MCP Registry currently supports the official crates.io registry (`https://crates.io`) only.

Cargo packages use `"registryType": "cargo"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/widget-mcp",
  "title": "Widget",
  "description": "Rust-native MCP server",
  "version": "0.3.0",
  "packages": [
    {
      "registryType": "cargo",
      "identifier": "widget-mcp",
      "version": "0.3.0",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

### Runtime Model

Cargo's runtime model differs from npm/PyPI/NuGet. `cargo install <crate>` places the compiled binary on PATH at `~/.cargo/bin`, after which MCP clients invoke it directly by name. There is no per-invocation runner equivalent to `npx` (npm), `uvx` (PyPI), or `dnx` (NuGet, .NET 10 SDK Preview 6+) — install is one-time, execution is by binary name. The Cargo example above intentionally omits `runtimeHint` for this reason.

Rust MCP authors have two first-class distribution paths:

- **Cargo (`registryType: cargo`)** — source-distributed via crates.io. End users need the Rust toolchain (`rustup`) to run `cargo install`. Idiomatic for the Rust ecosystem and consistent with how Rust CLIs are typically published.
- **MCPB (`registryType: mcpb`)** — prebuilt binary distributed via GitHub or GitLab Releases. End users need no toolchain. Right choice if the priority is "no Rust toolchain required."

Both paths are supported; the choice is the author's. Cargo native support exists so Rust authors who prefer source distribution are not forced into the MCPB binary-packaging workaround.

### Ownership Verification

The MCP Registry verifies ownership of Cargo packages by checking for the existence of an `mcp-name: $SERVER_NAME` string in the package README (which is rendered to HTML and served by crates.io's static CDN). The `$SERVER_NAME` portion **MUST** match the server name from `server.json`. For example:

```markdown README.md highlight={5}
# Widget MCP Server

A Rust-native MCP server for widget operations.

- MCP Registry name: `mcp-name: io.github.username/widget-mcp`
```

**Cargo-specific gotcha:** Unlike PyPI and NuGet (which preserve HTML comments in their README rendering), **crates.io strips HTML comments during markdown→HTML conversion**. The `<!-- mcp-name: ... -->` hidden-comment form that works for PyPI/NuGet **does not work for cargo** — the token will not appear in the rendered HTML the validator inspects. Cargo authors must include the `mcp-name:` token as visible markdown text. A simple bullet in the Links section is the recommended pattern.

## Docker/OCI Images

For Docker/OCI images, the MCP Registry currently supports:

- Docker Hub (`docker.io`)
- GitHub Container Registry (`ghcr.io`)
- Quay.io (`quay.io`)
- Google Artifact Registry (any `*.pkg.dev` domain)
- Azure Container Registry (`*.azurecr.io`)
- Microsoft Container Registry (`mcr.microsoft.com`)

Docker/OCI images use `"registryType": "oci"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/kubernetes-manager-mcp",
  "title": "Kubernetes Manager",
  "description": "Deploy and manage Kubernetes resources",
  "version": "1.0.0",
  "packages": [
    {
      "registryType": "oci",
      "identifier": "docker.io/yourusername/kubernetes-manager-mcp:1.0.0",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

The format of `identifier` is `registry/namespace/repository:tag`. For example, `docker.io/user/app:1.0.0`, `ghcr.io/user/app:1.0.0`, or `quay.io/myorg/my-mcp-server:1.0.0`. The tag can also be specified as a digest.

### Ownership Verification

The MCP Registry verifies ownership of Docker/OCI images by checking for an `io.modelcontextprotocol.server.name` annotation. The value of the `io.modelcontextprotocol.server.name` annotation **MUST** match the server name from `server.json`. For example:

```dockerfile Dockerfile
LABEL io.modelcontextprotocol.server.name="io.github.username/kubernetes-manager-mcp"
```

## MCPB Packages

For MCPB packages, the MCP Registry currently supports MCPB artifacts hosted via GitHub or GitLab releases.

MCPB packages use `"registryType": "mcpb"` in `server.json`. For example:

```json server.json highlight={9}
{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/image-processor-mcp",
  "title": "Image Processor",
  "description": "Process and transform images with various filters",
  "version": "1.0.0",
  "packages": [
    {
      "registryType": "mcpb",
      "identifier": "https://github.com/username/image-processor-mcp/releases/download/v1.0.0/image-processor.mcpb",
      "fileSha256": "fe333e598595000ae021bd27117db32ec69af6987f507ba7a63c90638ff633ce",
      "transport": {
        "type": "stdio"
      }
    }
  ]
}
```

### Verification

The MCPB package URL (`identifier` in `server.json`) **MUST** contain the string "mcp". That can be as part of the `.mcpb` file extension or in the name of the repository.

The package metadata in `server.json` **MUST** include a `fileSha256` property with a SHA-256 hash of the MCPB artifact, which can be computed using the `openssl` command:

```bash
openssl dgst -sha256 image-processor.mcpb
```

The MCP Registry does not validate this hash; however, MCP clients **do** validate the hash before installation to ensure file integrity. Downstream registries may also implement their own validation.