Mirror of https://github.com/modelcontextprotocol/registry — A community driven registry service for Model Context Protocol (MCP) servers.
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fc88cf0870Added schema validation and support for exhaustive and more detailed validation to existing validators. Added new `mcp-publisher validate` command. No change to any existing tests or behavior other than the new command. ## Motivation and Context Many currently published servers fail schema validation. Of those that pass, many have semantic/logical errors or other errors that make them impossible to configure, or their configuration when applied doesn't generate correct MCP server configuration (per their own documentation). To address this, we need better tooling to validate servers and to inform server publishers of errors, issues, and best practices in a way that is clear and actionable, both during server development and at time of publishing. I have started a discussion about the broader topic: https://github.com/modelcontextprotocol/registry/discussions/635 There is also a fairly detailed document describing the design, architecture, implementation, future plans, etc. See [Enhanced Validation Design](docs/explanations/proposed-enhanced-validation.md) This PR is the first step in the process of improving validation. It adds schema validation and updates all existing validators to use a new model that allows them to track context and return rich and exhaustive results. This has been done in a way that is backward compatible (ValidateServerJSON is unchanged as are all existing validation unit tests). There is a new `mcp-publisher` command called `validate` that is currenty the only place that schema validation and enhanced (exhaustive/rich) validation results are exposed. ### Changes Internal Validation improvements - Schema validation has been implemented and is available as an option in validation methods (defaults to off) - Existing validators track the JSON path (context) of the attribute they're evaluating, passing it to any child validators - Existing validators are exhaustive (return all issues, not failing fast on the first error) - Existing validators return rich validation results, including: - type (schema, semantic, linter) - severity (error, warn, info) - path (JSON path to server.json element) - reference (to the schema element or rule that triggered the result) - message (currently the same as previous error message) A new `validate` command has been added to `mcp-publisher` so publishers can evaluate their server.json before publishing - Includes new schema validation and previous semantic validation - Shows full details of all issues encountered during validation ### Usage Given a server.json that looks like this: ```json { "$schema": "https://static.modelcontextprotocol.io/schemas/2025-09-29/server.schema.json", "name": "io.github.BobDickinson/registry", "description": "An MCP server that provides [describe what your server does]", "repository": { "url": "", "source": "" }, "version": "=1.0.0", "packages": [ { "registryType": "oci", "registryBaseUrl": "https://docker.io", "identifier": "registry", "version": "1.0.0", "transport": { "type": "sse" }, "packageArguments": [ { "type": "named", "name": "--mode", "description": "Operation mode", "format": "foo" } ], "environmentVariables": [ { "description": "Your API key for the service", "isRequired": true, "format": "string", "isSecret": true, "name": "YOUR_API_KEY" } ] } ] } ``` Run the command: `mcp-publisher validate server.json` Which will produce the output: ```bash ❌ Validation failed with 5 issue(s): 1. [error] packages.0.packageArguments.0.format (schema) value must be one of "string", "number", "boolean", "filepath" Reference: #/definitions/Input/properties/format/enum from: [#/definitions/ServerDetail]/properties/packages/items/[#/definitions/Package]/properties/packageArguments/items/[#/definitions/Argument]/else/[#/definitions/NamedArgument]/allOf/0/[#/definitions/InputWithVariables]/allOf/0/[#/definitions/Input]/properties/format/enum 2. [error] packages.0.transport (schema) missing required fields: 'url' Reference: #/definitions/SseTransport/required from: [#/definitions/ServerDetail]/properties/packages/items/[#/definitions/Package]/properties/transport/else/else/[#/definitions/SseTransport]/required 3. [error] repository.url (schema) '' has invalid format 'uri' Reference: #/definitions/Repository/properties/url/format from: [#/definitions/ServerDetail]/properties/repository/[#/definitions/Repository]/properties/url/format 4. [error] version (semantic) version must be a specific version, not a range: "=1.0.0" Reference: version-looks-like-range 5. [error] packages[0].transport.url (semantic) url is required for sse transport type Reference: streamable-transport-url-required Error: validation failed ``` Note in the results above: - All errors contain the JSON path of the triggering element from server.json. - The first three errors are schema errors detected during schema validation. The `Reference` provided contains an absolute path to the schema rule that was violated, followed by the full schema path that enforced that rule (with $ref redirect values substited and enclosed in square brackets). - The error messages provided by the existing semantic validators are exactly the same as the previous error messages those validators produced. In the final solution we would remove semantic validators that are redundant to schema validation (as in number 5 above). We have the option to use the structured data produced by schema validation to replace the generic schema validation message with a more descriptive message if that is an issue (in particular, if the only argument for an ad-hoc validator is that is produces a better/cleaner message, we would just move that message creation code to the schema error result formatter and special case it as opposed to having a redundant validator). ### What's Next If this general direction is supported and this PR is accepted, a fast follow would include: - Add new validators (infliuenced by observed issues) for both semantic errors and best practices - Require passing schema validation (in addition to improved semantic validation) in order to publish - Remove existing validation code that is redundant to schema validation (ensuring error messages remain intelligible) - Update validation client code and tests to handle the new rich return types natively ### Issues Schema validation requires embedding the `server.schema.json` file into the validators package via `go:embed`, which is restricted from embedding files outside of the package. For this reason we copy the schema file into a schema subdir (via a prep target in the makefile) and we .gitignore it. I tried cleaning up the copy in the make clean target, but then the linter would complain about the embed target being missing if it wasn't there during development. I also considered just checking in the schema file and assuming a separate workflow for updating the embedded schema file, but it's not clear what that workflow would be or how it would be maintained. I'm open to a different approach, but the schema file does need to be embedded somehow for schema validation to work. ## How Has This Been Tested? All existing validation tests pass, new tests implemented and all pass. ## Breaking Changes No breaking changes, no behavior change except new `validate` command ## Types of changes <!-- What types of changes does your code introduce? Put an `x` in all the boxes that apply: --> - [ ] Bug fix (non-breaking change which fixes an issue) - [X] New feature (non-breaking change which adds functionality) - [ ] Breaking change (fix or feature that would cause existing functionality to change) - [ ] Documentation update ## Checklist <!-- Go over all the following points, and put an `x` in all the boxes that apply. --> - [X] I have read the [MCP Documentation](https://modelcontextprotocol.io) - [X] My code follows the repository's style guidelines - [X] New and existing tests pass locally - [X] I have added appropriate error handling - [X] I have added or updated documentation as needed --------- Co-authored-by: GitHub Action <action@github.com> |
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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:
- Adam Jones (Anthropic) @domdomegg
- Tadas Antanavicius (PulseMCP) @tadasant
- Toby Padilla (GitHub) @toby
- Radoslav (Rado) Dimitrov (Stacklok) @rdimitrov
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
- Docker
- Go 1.24.x
- ko - Container image builder for Go (installation instructions)
- golangci-lint v2.4.0
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-mcpyou must login to GitHub asdomdomegg, or be in a GitHub Action on domdomegg's reposme.adamjones/my-cool-mcpyou must prove ownership ofadamjones.mevia 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!