Mirror of https://github.com/modelcontextprotocol/registry — A community driven registry service for Model Context Protocol (MCP) servers.
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Tadas Antanavicius b58836c48e
feat: Add LocalTransport/RemoteTransport with URL template variables (#570)
Co-authored with Claude Code, but I've closely reviewed/modified/vetted
all changes; ready for final review.

## Summary

This PR adds LocalTransport and RemoteTransport separation with URL
template variable support for remote servers, enabling e.g. multi-tenant
deployments with configurable endpoints.

**Key additions:**
- LocalTransport (for Packages) and RemoteTransport (for Remotes)
- URL template variables for remote transports (e.g., `{tenant_id}` in
URLs)
- Pattern validation ensuring URLs are URL-like while allowing templates
- Full test coverage via Go validator tests and documentation examples

## ⚠️ server.json Update

This PR updates the `server.json` schema. A new schema version will be
cut after this lands.

## Problem

The current schema describes URL templating with `{curly_braces}` for
transports but provides no mechanism for Remote contexts to define what
those variables should resolve to, making the feature unusable for
remote servers.

Referenced issue: #394
- Users need multi-tenant remote servers with different endpoints per
deployment
- Each tenant/region has its own URL (e.g., `us-cell1.example.com`,
`emea-cell1.example.com`)
- Current schema doesn't support parameterized remote URLs

## Solution

### Schema Architecture

**LocalTransport** (for Package context):
```typescript
LocalTransport = StdioTransport | StreamableHttpTransport | SseTransport
```
- Used in Package context (non-breaking rename of existing behavior)
- Variables in `{curly_braces}` reference parent Package
arguments/environment variables
- Supports all three transport types including stdio

**RemoteTransport** (for Remote context):
```typescript
RemoteTransport = (StreamableHttpTransport | SseTransport) + { variables: object }
```
- Extends StreamableHttp/Sse via `allOf` composition - no duplication!
- Adds `variables` object for URL templating
- Only supports streamable-http and sse (stdio not valid for remotes)

### Key Changes

**1. Schema Updates** (`openapi.yaml`, `server.schema.json`):
- Added `LocalTransport` union type for Package context
- Added `RemoteTransport` with `allOf` composition extending base
transports
- Updated Package to reference `LocalTransport`
- Updated remotes to reference `RemoteTransport`
- Added URL pattern validation: `^https?://[^\\s]+$` to both
StreamableHttp and SSE
- Removed `format: uri` from SSE (was blocking template variables)

**2. Go Types** (`pkg/model/types.go`):
- Base `Transport` struct unchanged for Package context
- `RemoteTransport` struct for remotes with `Variables` field
- Both work with existing validation infrastructure

**3. Validators** (`internal/validators/`):
- `validateRemoteTransport()` validates Remote-specific constraints
- `collectRemoteTransportVariables()` extracts available variables
- `IsValidTemplatedURL()` validates template variables reference defined
variables
- `IsValidRemoteURL()` handles template variable substitution before
localhost check
- 6 new test cases for remote transport variable validation

**4. Documentation Examples** (`generic-server-json.md`):
- Remote Server with URL Templating (StreamableHttp with `{tenant_id}`)
- SSE Remote with URL Templating (SSE with `{tenant_id}`)
- Local Server with URL Templating (Package with `{port}`)
- All examples validate via existing `validate-examples` tool

## Example: Remote Transport with Variables

```json
{
  "remotes": [
    {
      "type": "streamable-http",
      "url": "https://api.example.com/mcp/{tenant_id}/{region}",
      "variables": {
        "tenant_id": {
          "description": "Tenant identifier",
          "isRequired": true,
          "choices": ["us-cell1", "emea-cell1", "apac-cell1"]
        },
        "region": {
          "description": "Deployment region",
          "isRequired": true
        }
      }
    }
  ]
}
```

Clients configure the variables, and `{tenant_id}` and `{region}` get
replaced to connect to tenant-specific endpoints like
`https://api.example.com/mcp/us-cell1/east`.

## Architecture Details

**Context-based variable resolution:**
- **Package + LocalTransport**: `{port}` references `--port` argument or
`PORT` env var from parent Package
- **Remote + RemoteTransport**: `{tenant_id}` references
`variables.tenant_id` defined in the transport itself
- **Code reuse**: StreamableHttp/Sse definitions shared via `allOf`, not
duplicated
- **Validation**: Template variables validated against available
variables for each context

---

## Follow-on Work

Follow-on work will be done to adopt the feedback in
https://github.com/modelcontextprotocol/registry/pull/570#issuecomment-3367417636
regarding variable naming/prioritzation/scoping conventions, but should
not have any impact on the shape being introduced here (just
validations).

---------

Co-authored-by: yuna0x0 <yuna@yuna0x0.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Connor Peet <connor@peet.io>
2025-12-11 09:17:32 -08:00
.githooks Add linting documentation and pre-commit hooks (#177) 2025-07-15 09:31:17 -07:00
.github Update Goreleaser and Cosign (#839) 2025-12-11 08:43:57 -08:00
.vscode Move publisher CLI from tools/ to cmd/ (#326) 2025-08-29 14:45:36 +01:00
cmd Fix issue-743 by sanitizing the URL (#809) 2025-12-04 09:23:15 -08:00
data Make mcpb package version optional and fix schema validation (#686) 2025-10-17 01:35:29 +03:00
deploy build(deps): bump github.com/pulumi/pulumi/sdk/v3 from 3.208.0 to 3.210.0 in /deploy (#817) 2025-12-04 12:28:03 +02:00
docs feat: Add LocalTransport/RemoteTransport with URL template variables (#570) 2025-12-11 09:17:32 -08:00
internal feat: Add LocalTransport/RemoteTransport with URL template variables (#570) 2025-12-11 09:17:32 -08:00
pkg feat: Add LocalTransport/RemoteTransport with URL template variables (#570) 2025-12-11 09:17:32 -08:00
scripts docs: update API endpoint documentation from /v0/ to /v0.1/ (#802) 2025-12-04 13:02:45 -08:00
tests/integration Use ko in favour of docker build (#708) 2025-10-29 15:16:11 +00:00
tools feat: Add LocalTransport/RemoteTransport with URL template variables (#570) 2025-12-11 09:17:32 -08:00
.env.example fix: seed from production API by default to ensure validation passes (#611) 2025-10-03 23:58:37 +03:00
.gitignore Prepare docs for modelcontextprotocol.io (#728) 2025-11-18 17:22:31 +00:00
.golangci.yml Enable gofmt in golangci (#597) 2025-10-02 16:25:11 +01:00
.goreleaser.yaml Update Goreleaser and Cosign (#839) 2025-12-11 08:43:57 -08:00
.ko.dockerignore Use ko in favour of docker build (#708) 2025-10-29 15:16:11 +00:00
.ko.yaml Use ko in favour of docker build (#708) 2025-10-29 15:16:11 +00:00
CLAUDE.md Consolidate documentation and remove redundancy (#222) 2025-08-06 16:05:07 +01:00
complete.md Fix NuGet.org base URL default, improve API integration (#813) 2025-12-09 07:19:38 -08:00
docker-compose.yml Use ko in favour of docker build (#708) 2025-10-29 15:16:11 +00:00
go.mod build(deps): bump go.opentelemetry.io/otel/exporters/prometheus from 0.60.0 to 0.61.0 (#832) 2025-12-10 23:57:22 +02:00
go.sum build(deps): bump go.opentelemetry.io/otel/exporters/prometheus from 0.60.0 to 0.61.0 (#832) 2025-12-10 23:57:22 +02:00
LICENSE Update LICENSE copyright holder to MCP Contributors (#293) 2025-08-21 09:11:42 -06:00
Makefile Ensure tests are failing CI (#840) 2025-12-11 09:56:57 +02:00
README.md Fix broken links in README (#786) 2025-11-18 22:11:41 -08:00

MCP Registry

The MCP registry provides MCP clients with a list of MCP servers, like an app store for MCP servers.

📤 Publish my MCP server | ⚡️ Live API docs | 👀 Ecosystem vision | 📖 Full documentation

Development Status

2025-10-24 update: The Registry API has entered an API freeze (v0.1) 🎉. For the next month or more, the API will remain stable with no breaking changes, allowing integrators to confidently implement support. This freeze applies to v0.1 while development continues on v0. We'll use this period to validate the API in real-world integrations and gather feedback to shape v1 for general availability. Thank you to everyone for your contributions and patience—your involvement has been key to getting us here!

2025-09-08 update: The registry has launched in preview 🎉 (announcement blog post). While the system is now more stable, this is still a preview release and breaking changes or data resets may occur. A general availability (GA) release will follow later. We'd love your feedback in GitHub discussions or in the #registry-dev Discord (joining details here).

Current key maintainers:

Contributing

We use multiple channels for collaboration - see modelcontextprotocol.io/community/communication.

Often (but not always) ideas flow through this pipeline:

  • Discord - Real-time community discussions
  • Discussions - Propose and discuss product/technical requirements
  • Issues - Track well-scoped technical work
  • Pull Requests - Contribute work towards issues

Quick start:

Pre-requisites

Running the server

# Start full development environment
make dev-compose

This starts the registry at localhost:8080 with PostgreSQL. The database uses ephemeral storage and is reset each time you restart the containers, ensuring a clean state for development and testing.

Note: The registry uses ko to build container images. The make dev-compose command automatically builds the registry image with ko and loads it into your local Docker daemon before starting the services.

By default, the registry seeds from the production API with a filtered subset of servers (to keep startup fast). This ensures your local environment mirrors production behavior and all seed data passes validation. For offline development you can seed from a file without validation with MCP_REGISTRY_SEED_FROM=data/seed.json MCP_REGISTRY_ENABLE_REGISTRY_VALIDATION=false make dev-compose.

The setup can be configured with environment variables in docker-compose.yml - see .env.example for a reference.

Alternative: Running a pre-built Docker image

Pre-built Docker images are automatically published to GitHub Container Registry:

# Run latest stable release
docker run -p 8080:8080 ghcr.io/modelcontextprotocol/registry:latest

# Run latest from main branch (continuous deployment)
docker run -p 8080:8080 ghcr.io/modelcontextprotocol/registry:main

# Run specific release version
docker run -p 8080:8080 ghcr.io/modelcontextprotocol/registry:v1.0.0

# Run development build from main branch
docker run -p 8080:8080 ghcr.io/modelcontextprotocol/registry:main-20250906-abc123d

Available tags:

  • Releases: latest, v1.0.0, v1.1.0, etc.
  • Continuous: main (latest main branch build)
  • Development: main-<date>-<sha> (specific commit builds)

Publishing a server

To publish a server, we've built a simple CLI. You can use it with:

# Build the latest CLI
make publisher

# Use it!
./bin/mcp-publisher --help

See the publisher guide for more details.

Other commands

# Run lint, unit tests and integration tests
make check

There are also a few more helpful commands for development. Run make help to learn more, or look in Makefile.

Architecture

Project Structure

├── cmd/                     # Application entry points
│   └── publisher/           # Server publishing tool
├── data/                    # Seed data
├── deploy/                  # Deployment configuration (Pulumi)
├── docs/                    # Documentation
├── internal/                # Private application code
│   ├── api/                 # HTTP handlers and routing
│   ├── auth/                # Authentication (GitHub OAuth, JWT, namespace blocking)
│   ├── config/              # Configuration management
│   ├── database/            # Data persistence (PostgreSQL)
│   ├── service/             # Business logic
│   ├── telemetry/           # Metrics and monitoring
│   └── validators/          # Input validation
├── pkg/                     # Public packages
│   ├── api/                 # API types and structures
│   │   └── v0/              # Version 0 API types
│   └── model/               # Data models for server.json
├── scripts/                 # Development and testing scripts
├── tests/                   # Integration tests
└── tools/                   # CLI tools and utilities
    └── validate-*.sh        # Schema validation tools

Authentication

Publishing supports multiple authentication methods:

  • GitHub OAuth - For publishing by logging into GitHub
  • GitHub OIDC - For publishing from GitHub Actions
  • DNS verification - For proving ownership of a domain and its subdomains
  • HTTP verification - For proving ownership of a domain

The registry validates namespace ownership when publishing. E.g. to publish...:

  • io.github.domdomegg/my-cool-mcp you must login to GitHub as domdomegg, or be in a GitHub Action on domdomegg's repos
  • me.adamjones/my-cool-mcp you must prove ownership of adamjones.me via DNS or HTTP challenge

Community Projects

Check out community projects to explore notable registry-related work created by the community.

More documentation

See the documentation for more details if your question has not been answered here!