modelcontextprotocol · toby · Jul 7, 2025 · Jul 7, 2025 · Jul 7, 2025
diff --git a/docs/README.md b/docs/README.md
@@ -16,4 +16,8 @@
 
 [`api_examples.md`](./api_examples.md) - Examples of what data will actually look like coming from the official registry API
 
-[`architecture.md`](./architecture.md) - Technical architecture, deployment strategies, and data flows
+[`architecture.md`](./architecture.md) - Technical architecture, deployment strategies, and data flows
+
+[`server.json` README](./server-json/README.md) - description of the `server.json` purpose and schema
+
+[`new_package_registry.md`](./new_package_registry.md) - steps to add a new package registry for local server packages
diff --git a/docs/architecture.md b/docs/architecture.md
@@ -31,6 +31,7 @@ graph TB
         NPM[npm Registry]
         PYPI[PyPI Registry]
         DOCKER[Docker Hub]
+        NUGET[NuGet Gallery]
         DNS[DNS Services]
         GH[GitHub OAuth]
     end
@@ -46,6 +47,7 @@ graph TB
     API -.-> |Verify| DNS
     API -.-> |Reference| NPM
     API -.-> |Reference| PYPI
+    API -.-> |Reference| NUGET
     API -.-> |Reference| DOCKER
 ```
 

diff --git a/docs/design_principles.md b/docs/design_principles.md
@@ -9,7 +9,7 @@ The registry serves as the authoritative metadata repository for publicly-availa
 ## 2. Minimal Operational Burden
 
 - Design for low maintenance and operational overhead
-- Delegate complexity to existing services where possible (GitHub for auth, npm/PyPI for packages)
+- Delegate complexity to existing services where possible (GitHub for auth, npm/PyPI/NuGet for packages)
 - Avoid features that require constant human intervention or moderation
 - Build for reasonable downtime tolerance (24h acceptable) by having consumers cache data for their end-users
 
@@ -21,7 +21,7 @@ The registry serves as the authoritative metadata repository for publicly-availa
 
 ## 4. Meets Industry Security Standards
 
-- Leverage existing package registries (npm, PyPI, Docker Hub, etc.) for source code distribution, obviating the need to reinvent source code security
+- Leverage existing package registries (npm, PyPI, NuGet, Docker Hub, etc.) for source code distribution, obviating the need to reinvent source code security
 - Use mechanisms like DNS verification, OAuth to provide base layer of authentication and trust
 - Implement rate limiting, field validation, and blacklisting to prevent abuse
 

diff --git a/docs/faq.md b/docs/faq.md
@@ -15,7 +15,7 @@ The MCP Registry is the official centralized metadata repository for publicly-ac
 
 ### Is the MCP Registry a package registry?
 
-No. The MCP Registry stores metadata about MCP servers and references to where they're hosted (npm, PyPI, Docker Hub, etc.), but does not host the actual source code or packages.
+No. The MCP Registry stores metadata about MCP servers and references to where they're hosted (npm, PyPI, NuGet, Docker Hub, etc.), but does not host the actual source code or packages.
 
 ### Who should use the MCP Registry directly?
 
@@ -37,7 +37,7 @@ Servers are published by submitting a `server.json` file through our CLI tool. T
 
 1. GitHub authentication
 2. A public GitHub repository (even for closed-source servers - just for the metadata)
-3. Your server package published to a supported registry (npm, PyPI, Docker Hub, etc.)
+3. Your server package published to a supported registry (npm, PyPI, NuGet, Docker Hub, etc.)
 4. Optional: DNS verification for custom namespacing
 
 ### What namespaces are available?
@@ -54,6 +54,7 @@ No. While open source code is encouraged, it is not required for either locally
 
 - npm (Node.js packages)
 - PyPI (Python packages)
+- NuGet.org (.NET packages)
 - GitHub Container Registry (GHCR)
 
 More can be added as the community desires; feel free to open an issue if you are interested in building support for another registry.

diff --git a/docs/new_package_registry.md b/docs/new_package_registry.md
@@ -0,0 +1,39 @@
+# Adding a new package registry
+
+The MCP Registry project is a **metaregistry**, meaning that it hosts metadata for MCP servers but does not host the code for the servers directly.
+
+For local MCP servers, the MCP Registry has pointers in the `packages` node of the [`server.json`](server-json/README.md) schema that refer to packages in supported package managers.
+
+The list of supported package managers for hosting MCP servers is defined by the `properties.packages[N].properties.registry_name` string enum in the [`server.json` schema](server-json/schema.json). For example, this could be "npm" (for npmjs.com packages) or "pypi" (for PyPI packages).
+
+For remote MCP servers, the package registry is not relevant. The MCP client consumes the server via a URL instead of by downloading and running a package. In other words, this document only applies to local MCP servers.
+
+For the sake of illustration, this document will use npm (the Node.js package manager) as an example at each step.
+
+## Prerequisites
+
+The package registry must meet the following requirements:
+
+1. The package registry supports packaging and executing CLI apps. Local MCP servers use the [stdio transport](https://modelcontextprotocol.io/docs/concepts/transports#standard-input%2Foutput-stdio).
+   - npm CLI tools typically express their CLI commands in the [`bin` property of the package.json](https://docs.npmjs.com/cli/v11/configuring-npm/package-json#bin)
+1. The package registry (or associated client tooling) has a widely accepted **single-shot** CLI command.
+   - npm's `npx` tool executes CLI commands using a [documented execution heuristic](https://docs.npmjs.com/cli/v11/commands/npx#description)
+   - For example, the MCP client can map the `server.json` metadata to an `npx` CLI execution, with args and environment variables populated via user input.
+1. The package registry supports anonymous package downloads. This allows the MCP client software to use the metadata found in the MCP registry to discover, download, and execute package-based local MCP servers with minimal user intervention.
+   - `npx` by default connects to the public npmjs.com registry, allowing simple consumption of public npm packages.
+
+## Steps
+
+These steps are currently very brief because the MCP Registry service is not yet deployed to production. These steps may evolve as additional validations or details are discovered and mandated.
+
+1. [Create a feature request issue](https://github.com/modelcontextprotocol/registry/issues/new?template=feature_request.md) on the MCP Registry repository to begin the discussion about adding the package registry.
+   - Example for NuGet: https://github.com/modelcontextprotocol/registry/issues/126
+1. Open a PR with the following changes:
+   - Update the [`server.json` schema](server-json/schema.json)
+     - Add your package registry name to the `registry_name` enum value array.
+     - Add the single-shot CLI command name to the `runtime_hint` example value array.
+   - Update the [`openapi.yaml`](openapi.yaml)
+     - Add your package registry name to the `registry_name` enum value array.
+     - Add the single-shot CLI command name to the `runtime_hint` example value array.
+     - This duplicates the previous step and will be improved with [issue #159](https://github.com/modelcontextprotocol/registry/issues/159).
+   - Add a sample, minimal `server.json` to the [`server.json` examples](server-json/examples.md).
diff --git a/docs/openapi.yaml b/docs/openapi.yaml
@@ -171,7 +171,7 @@ components:
       properties:
         registry_name:
           type: string
-          enum: [npm, docker, pypi, homebrew]
+          enum: [npm, docker, pypi, homebrew, nuget]
           example: "npm"
         name:
           type: string
@@ -182,7 +182,7 @@ components:
         runtime_hint:
           type: string
           description: A hint to help clients determine the appropriate runtime for the package. This field should be provided when `runtime_arguments` are present.
-          examples: [npx, uvx]
+          examples: [npx, uvx, dnx]
         runtime_arguments:
           type: array
           description: A list of arguments to be passed to the package's runtime command (such as docker or npx). The `runtime_hint` field should be provided when `runtime_arguments` are present.

diff --git a/docs/server-json/examples.md b/docs/server-json/examples.md
@@ -179,6 +179,41 @@
 }
 ```
 
+## NuGet (.NET) Package Example
+
+The `dnx` tool ships with the .NET 10 SDK, starting with Preview 6.
+
+```json
+{
+  "name": "Knapcode.SampleMcpServer",
+  "description": "Sample NuGet MCP server for a random number and random weather",
+  "repository": {
+    "url": "https://github.com/joelverhagen/Knapcode.SampleMcpServer",
+    "source": "github"
+  },
+  "version_detail": {
+    "version": "0.3.0",
+    "release_date": "2025-07-02T18:54:28.00Z"
+  },
+  "packages": [
+    {
+      "registry_name": "nuget",
+      "name": "Knapcode.SampleMcpServer",
+      "version": "0.3.0-beta",
+      "runtime_hint": "dnx",
+      "environment_variables": [
+        {
+          "name": "WEATHER_CHOICES",
+          "description": "Comma separated list of weather descriptions to randomly select.",
+          "is_required": true,
+          "is_secret": false
+        }
+      ]
+    }
+  ]
+}
+```
+
 ## Complex Docker Server with Multiple Arguments
 
 ```json

diff --git a/docs/server-json/schema.json b/docs/server-json/schema.json
@@ -88,7 +88,8 @@
               "npm",
               "docker",
               "pypi",
-              "homebrew"
+              "homebrew",
+              "nuget"
             ],
             "description": "Package registry type",
             "example": "npm"
@@ -105,10 +106,11 @@
           },
           "runtime_hint": {
             "type": "string",
-            "description": "Hint for appropriate runtime (e.g., npx, uvx)",
+            "description": "Hint for appropriate runtime (e.g., npx, uvx, dnx)",
             "examples": [
               "npx",
-              "uvx"
+              "uvx",
+              "dnx"
             ]
           },
           "runtime_arguments": {

diff --git a/tools/publisher/server.json b/tools/publisher/server.json
@@ -24,7 +24,7 @@
                 }
             ]
         },{
-            "registry_name": "docker>",
+            "registry_name": "docker",
             "name": "io.github.<owner>/<server-name>-cli",
             "version": "0.123.223",
             "runtime_hint": "docker",