Align the server.json schema with the YAML (#168)

<!-- Provide a brief summary of your changes -->

## Motivation and Context

This is in support of
https://github.com/modelcontextprotocol/registry/issues/159, to make it
easier, I hope. My team noticed some differences in the JSON schema,
most notably the "choices" property was missing. I tried to write a tool
to do this but slowed down since I am not experienced with Go. This is a
first pass, maybe someone else can finish the tooling.

I restructured the JSON schema to break out child objects like the YAML
file, and brought the descriptions and example into sync. The only
differences are two extra properties in the YAML which are computed by
the server:

- `VersionDetail.is_latest` is not present in the JSON schema, computed
by the registry based on
https://github.com/modelcontextprotocol/registry/issues/158
- `Server.id` is not present in the JSON schema, generated by the
registry

The idea is the a tool could look at ServerDetail in the YAML and then
generate the schema.json with minimal fix-ups (add a root title, remove
`VersionDetail.is_latest` and `Server.id`.

~Question for @tadasant - should `VersionDetail.release_date` be in the
JSON schema? I think _no_ (and let it be computed) but it's there right
now.~ - aligned with
https://github.com/modelcontextprotocol/registry/pull/167 and removed

## How Has This Been Tested?

I have tested the JSON schema against the sample server.json in the repo
(files and markdown blocks).

## Breaking Changes

None.

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] 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
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->
This commit is contained in:
Joel Verhagen 2025-07-09 13:27:38 -04:00 • committed by GitHub
commit 6a2e5d1b27
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@ -1,27 +1,10 @@
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"title": "MCP Server Detail",
"description": "Schema for a static representation of an MCP server. Used in various contexts related to discovery, installation, and configuration.",
"type": "object",
"required": [
"name",
"description",
"version_detail"
],
"properties": {
"name": {
"type": "string",
"description": "Server name/identifier",
"example": "io.modelcontextprotocol/filesystem"
},
"description": {
"type": "string",
"description": "Human-readable description of the server's functionality",
"example": "Node.js server implementing Model Context Protocol (MCP) for filesystem operations."
},
"repository": {
"$ref": "#/$defs/ServerDetail",
"$defs": {
"Repository": {
"type": "object",
"description": "Canonical source repository information",
"required": [
"url",
"source",
@ -31,7 +14,6 @@
"url": {
"type": "string",
"format": "uri",
"description": "Repository URL",
"example": "https://github.com/modelcontextprotocol/servers"
},
"source": {
@ -40,197 +22,185 @@
"github",
"gitlab"
],
"description": "Repository hosting service",
"example": "github"
},
"id": {
"type": "string",
"description": "Repository identifier unique and immutable in the corresponding source",
"example": "b94b5f7e-c7c6-d760-2c78-a5e9b8a5b8c9"
}
}
},
"version_detail": {
"VersionDetail": {
"type": "object",
"description": "Version information for this server",
"required": [
"version",
"release_date"
"version"
],
"properties": {
"version": {
"type": "string",
"description": "Server version (equivalent to Implementation.version in MCP spec)",
"example": "1.0.2"
},
"release_date": {
"type": "string",
"format": "date-time",
"description": "When this version was published to the registry",
"example": "2023-06-15T10:30:00Z"
"example": "1.0.2",
"description": "Equivalent of Implementation.version in MCP specification."
}
}
},
"packages": {
"type": "array",
"description": "Available package distributions",
"items": {
"type": "object",
"required": [
"registry_name",
"name",
"version"
],
"properties": {
"registry_name": {
"type": "string",
"enum": [
"npm",
"docker",
"pypi",
"homebrew",
"nuget"
],
"description": "Package registry type",
"example": "npm"
},
"name": {
"type": "string",
"description": "Package name in the registry",
"example": "@modelcontextprotocol/server-filesystem"
},
"version": {
"type": "string",
"description": "Package version",
"example": "1.0.2"
},
"runtime_hint": {
"type": "string",
"description": "Hint for appropriate runtime (e.g., npx, uvx, dnx)",
"examples": [
"npx",
"uvx",
"dnx"
]
},
"runtime_arguments": {
"type": "array",
"description": "Arguments for the runtime command (docker, npx, etc.)",
"items": {
"$ref": "#/$defs/argument"
}
},
"package_arguments": {
"type": "array",
"description": "Arguments for the package binary",
"items": {
"$ref": "#/$defs/argument"
}
},
"environment_variables": {
"type": "array",
"description": "Environment variables to set",
"items": {
"$ref": "#/$defs/key_value_input"
}
}
}
}
},
"remotes": {
"type": "array",
"description": "Remote server endpoints",
"items": {
"type": "object",
"required": [
"transport_type",
"url"
],
"properties": {
"transport_type": {
"type": "string",
"enum": [
"streamable",
"sse"
],
"description": "Transport protocol type",
"example": "sse"
},
"url": {
"type": "string",
"format": "uri",
"description": "Remote server URL",
"example": "https://mcp-fs.example.com/sse"
},
"headers": {
"type": "array",
"description": "HTTP headers to include",
"items": {
"$ref": "#/$defs/key_value_input"
}
}
}
}
}
},
"$defs": {
"variable_map": {
"type": "object",
"description": "A map of variable names to their values. Keys in the input `value` that are wrapped in `{curly_braces}` will be replaced with the corresponding variable values.",
"additionalProperties": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"format": {
"type": "string",
"description": "Specifies the input format. Supported values include `filepath`, which should be interpreted as a file on the user's filesystem.\n\nWhen the input is converted to a string, booleans should be represented by the strings \"true\" and \"false\", and numbers should be represented as decimal values.",
"enum": [
"string",
"number",
"boolean",
"filepath"
],
"default": "string"
},
"is_required": {
"type": "boolean"
},
"default": {
"type": "string"
}
}
}
},
"key_value_input": {
"Server": {
"type": "object",
"required": [
"name"
"name",
"description",
"version_detail"
],
"properties": {
"name": {
"type": "string",
"description": "Variable name"
"description": "Server name/identifier",
"example": "io.modelcontextprotocol/filesystem"
},
"description": {
"type": "string"
"type": "string",
"description": "Human-readable description of the server's functionality",
"example": "Node.js server implementing Model Context Protocol (MCP) for filesystem operations."
},
"default": {
"repository": {
"$ref": "#/$defs/Repository"
},
"version_detail": {
"$ref": "#/$defs/VersionDetail"
}
}
},
"Package": {
"type": "object",
"required": [
"registry_name",
"name",
"version"
],
"properties": {
"registry_name": {
"type": "string",
"enum": [
"npm",
"docker",
"pypi",
"homebrew",
"nuget"
],
"description": "Package registry type",
"example": "npm"
},
"name": {
"type": "string",
"description": "Package name in the registry",
"example": "io.modelcontextprotocol/filesystem"
},
"version": {
"type": "string",
"description": "Package version",
"example": "1.0.2"
},
"runtime_hint": {
"type": "string",
"description": "A hint to help clients determine the appropriate runtime for the package. This field should be provided when `runtime_arguments` are present.",
"examples": [
"npx",
"uvx",
"dnx"
]
},
"runtime_arguments": {
"type": "array",
"description": "A list of arguments to be passed to the package's runtime command (such as docker or npx). The `runtime_hint` field should be provided when `runtime_arguments` are present.",
"items": {
"$ref": "#/$defs/Argument"
}
},
"package_arguments": {
"type": "array",
"description": "A list of arguments to be passed to the package's binary.",
"items": {
"$ref": "#/$defs/Argument"
}
},
"environment_variables": {
"type": "array",
"description": "A mapping of environment variables to be set when running the package.",
"items": {
"$ref": "#/$defs/KeyValueInput"
}
}
}
},
"Input": {
"type": "object",
"properties": {
"description": {
"description": "A description of the input, which clients can use to provide context to the user.",
"type": "string"
},
"is_required": {
"type": "boolean",
"default": false
},
"format": {
"type": "string",
"description": "Specifies the input format. Supported values include `filepath`, which should be interpreted as a file on the user's filesystem.\n\nWhen the input is converted to a string, booleans should be represented by the strings \"true\" and \"false\", and numbers should be represented as decimal values.",
"enum": [
"string",
"number",
"boolean",
"filepath"
],
"default": "string"
},
"value": {
"type": "string",
"description": "The default value for the input. If this is not set, the user may be prompted to provide a value. If a value is set, it should not be configurable by end users.\n\nIdentifiers wrapped in `{curly_braces}` will be replaced with the corresponding properties from the input `variables` map. If an identifier in braces is not found in `variables`, or if `variables` is not provided, the `{curly_braces}` substring should remain unchanged.\n"
},
"is_secret": {
"type": "boolean",
"description": "Indicates whether the input is a secret value (e.g., password, token). If true, clients should handle the value securely.",
"default": false
},
"default": {
"type": "string",
"description": "The default value for the input."
},
"choices": {
"type": "array",
"description": "A list of possible values for the input. If provided, the user must select one of these values.",
"items": {
"type": "string"
},
"example": []
}
}
},
"argument": {
"oneOf": [
"InputWithVariables": {
"allOf": [
{
"$ref": "#/$defs/Input"
},
{
"type": "object",
"properties": {
"variables": {
"type": "object",
"description": "A map of variable names to their values. Keys in the input `value` that are wrapped in `{curly_braces}` will be replaced with the corresponding variable values.",
"additionalProperties": {
"$ref": "#/$defs/Input"
}
}
}
}
]
},
"PositionalArgument": {
"description": "A positional input is a value inserted verbatim into the command line.",
"allOf": [
{
"$ref": "#/$defs/InputWithVariables"
},
{
"type": "object",
"required": [
@ -239,34 +209,31 @@
],
"properties": {
"type": {
"const": "positional"
"type": "string",
"enum": [
"positional"
],
"example": "positional"
},
"value_hint": {
"type": "string",
"description": "An identifier-like hint for the value. This is not part of the command line, but can be used by client configuration and to provide hints to users."
},
"description": {
"type": "string"
},
"value": {
"type": "string",
"description": "The default value for the input. If this is not set, the user may be prompted to provide a value.\n\nIdentifiers wrapped in `{curly_braces}` will be replaced with the corresponding properties from the input `variables` map. If an identifier in braces is not found in `variables`, or if `variables` is not provided, the `{curly_braces}` substring should remain unchanged."
},
"default": {
"type": "string"
},
"is_required": {
"type": "boolean",
"default": false
"description": "An identifier-like hint for the value. This is not part of the command line, but can be used by client configuration and to provide hints to users.",
"example": "file_path"
},
"is_repeated": {
"type": "boolean",
"description": "Whether the argument can be repeated multiple times in the command line.",
"default": false
},
"variables": {
"$ref": "#/$defs/variable_map"
}
}
}
]
},
"NamedArgument": {
"description": "A command-line `--flag={value}`.",
"allOf": [
{
"$ref": "#/$defs/InputWithVariables"
},
{
"type": "object",
@ -276,29 +243,107 @@
],
"properties": {
"type": {
"const": "named"
"type": "string",
"enum": [
"named"
],
"example": "named"
},
"name": {
"type": "string",
"description": "Flag name including dashes"
},
"description": {
"type": "string"
},
"value": {
"type": "string",
"description": "The default value for the input. If this is not set, the user may be prompted to provide a value.\n\nIdentifiers wrapped in `{curly_braces}` will be replaced with the corresponding properties from the input `variables` map. If an identifier in braces is not found in `variables`, or if `variables` is not provided, the `{curly_braces}` substring should remain unchanged."
},
"is_required": {
"type": "boolean",
"default": false
"description": "The flag name, including any leading dashes.",
"example": "--port"
},
"is_repeated": {
"type": "boolean",
"description": "Whether the argument can be repeated multiple times.",
"default": false
}
}
}
]
},
"KeyValueInput": {
"allOf": [
{
"$ref": "#/$defs/InputWithVariables"
},
{
"type": "object",
"required": [
"name"
],
"properties": {
"name": {
"type": "string",
"description": "Name of the header or environment variable.",
"example": "SOME_VARIABLE"
}
}
}
]
},
"Argument": {
"anyOf": [
{
"$ref": "#/$defs/PositionalArgument"
},
{
"$ref": "#/$defs/NamedArgument"
}
]
},
"Remote": {
"type": "object",
"required": [
"transport_type",
"url"
],
"properties": {
"transport_type": {
"type": "string",
"enum": [
"streamable",
"sse"
],
"description": "Transport protocol type",
"example": "sse"
},
"url": {
"type": "string",
"format": "uri",
"description": "Remote server URL",
"example": "https://mcp-fs.example.com/sse"
},
"headers": {
"type": "array",
"description": "HTTP headers to include",
"items": {
"$ref": "#/$defs/KeyValueInput"
}
}
}
},
"ServerDetail": {
"description": "Schema for a static representation of an MCP server. Used in various contexts related to discovery, installation, and configuration.",
"allOf": [
{
"$ref": "#/$defs/Server"
},
{
"type": "object",
"properties": {
"packages": {
"type": "array",
"items": {
"$ref": "#/$defs/Package"
}
},
"variables": {
"$ref": "#/$defs/variable_map"
"remotes": {
"type": "array",
"items": {
"$ref": "#/$defs/Remote"
}
}
}
}