9ce229d337- Clarified `value` field description to remove incorrect 'default'
wording
- Improved `valueHint` description to clarify its form and purpose
(labels and variable substitution)
- Fixed NamedArgument `description` to use correct flag syntax (--flag
{value})
- Enhanced `default` field description with guidance on valid values and
when to use placeholder instead
- Added optional Input `placeholder` field for input guidance and
examples
<!-- Provide a brief summary of your changes -->
## Motivation and Context
After implementing a configuration UX for the registry supporting all
schema elements, performing schema validation on all published servers
and analyzing failures, and hand reviewing approximately a hundred
server configurations, I found a number of concerning issues
(essentially misconfigurations, verified by the docs of the server in
question, which often did not fail schema validation). I also found
"proper" configurations which disagreed with the schema guidance (for
example, all named args usage).
I documented those issues and my recommendations here:
https://github.com/modelcontextprotocol/registry/discussions/572
The fairly modest changes in this PR will address these issues (or at
least make the correct usage more clear so that we can give more
explicit guidance that is consistent with the new schema, and generally
clean up these misconfiguration).
## How Has This Been Tested?
I used my own schema validation script to apply this schema to all
published servers. The changes are only documentation (description
updates) and the addition of a new field property, so no validation
behavior change was intended nor was any observed.
## Breaking Changes
No breaking changes
## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [X] New feature (non-breaking change which adds functionality)
- [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)
- [ ] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed
466 lines
17 KiB
JSON
466 lines
17 KiB
JSON
{
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"$schema": "http://json-schema.org/draft-07/schema#",
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"$id": "https://static.modelcontextprotocol.io/schemas/2025-09-29/server.schema.json",
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"title": "MCP Server Detail",
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"$ref": "#/definitions/ServerDetail",
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"definitions": {
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"Repository": {
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"type": "object",
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"description": "Repository metadata for the MCP server source code. Enables users and security experts to inspect the code, improving transparency.",
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"required": [
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"url",
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"source"
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],
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"properties": {
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"url": {
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"type": "string",
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"format": "uri",
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"description": "Repository URL for browsing source code. Should support both web browsing and git clone operations.",
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"example": "https://github.com/modelcontextprotocol/servers"
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},
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"source": {
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"type": "string",
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"description": "Repository hosting service identifier. Used by registries to determine validation and API access methods.",
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"example": "github"
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},
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"id": {
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"type": "string",
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"description": "Repository identifier from the hosting service (e.g., GitHub repo ID). Owned and determined by the source forge. Should remain stable across repository renames and may be used to detect repository resurrection attacks - if a repository is deleted and recreated, the ID should change. For GitHub, use: gh api repos/<owner>/<repo> --jq '.id'",
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"example": "b94b5f7e-c7c6-d760-2c78-a5e9b8a5b8c9"
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},
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"subfolder": {
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"type": "string",
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"description": "Optional relative path from repository root to the server location within a monorepo or nested package structure. Must be a clean relative path.",
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"example": "src/everything"
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}
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}
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},
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"Package": {
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"type": "object",
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"additionalProperties": false,
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"required": [
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"registryType",
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"identifier",
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"version",
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"transport"
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],
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"properties": {
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"registryType": {
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"type": "string",
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"description": "Registry type indicating how to download packages (e.g., 'npm', 'pypi', 'oci', 'nuget', 'mcpb')",
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"examples": ["npm", "pypi", "oci", "nuget", "mcpb"]
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},
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"registryBaseUrl": {
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"type": "string",
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"format": "uri",
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"description": "Base URL of the package registry",
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"examples": ["https://registry.npmjs.org", "https://pypi.org", "https://docker.io", "https://api.nuget.org", "https://github.com", "https://gitlab.com"]
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},
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"identifier": {
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"type": "string",
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"description": "Package identifier - either a package name (for registries) or URL (for direct downloads)",
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"examples": ["@modelcontextprotocol/server-brave-search", "https://github.com/example/releases/download/v1.0.0/package.mcpb"]
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},
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"version": {
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"type": "string",
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"description": "Package version. Must be a specific version. Version ranges are rejected (e.g., '^1.2.3', '~1.2.3', '>=1.2.3', '1.x', '1.*').",
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"not": {
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"const": "latest"
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},
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"example": "1.0.2",
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"minLength": 1
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},
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"fileSha256": {
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"type": "string",
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"pattern": "^[a-f0-9]{64}$",
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"description": "SHA-256 hash of the package file for integrity verification. Required for MCPB packages and optional for other package types. Authors are responsible for generating correct SHA-256 hashes when creating server.json. If present, MCP clients must validate the downloaded file matches the hash before running packages to ensure file integrity.",
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"example": "fe333e598595000ae021bd27117db32ec69af6987f507ba7a63c90638ff633ce"
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},
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"runtimeHint": {
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"type": "string",
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"description": "A hint to help clients determine the appropriate runtime for the package. This field should be provided when `runtimeArguments` are present.",
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"examples": [
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"npx",
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"uvx",
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"docker",
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"dnx"
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]
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},
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"transport": {
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"anyOf": [
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{
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"$ref": "#/definitions/StdioTransport"
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},
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{
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"$ref": "#/definitions/StreamableHttpTransport"
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},
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{
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"$ref": "#/definitions/SseTransport"
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}
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],
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"description": "Transport protocol configuration for the package"
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},
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"runtimeArguments": {
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"type": "array",
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"description": "A list of arguments to be passed to the package's runtime command (such as docker or npx). The `runtimeHint` field should be provided when `runtimeArguments` are present.",
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"items": {
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"$ref": "#/definitions/Argument"
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}
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},
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"packageArguments": {
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"type": "array",
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"description": "A list of arguments to be passed to the package's binary.",
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"items": {
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"$ref": "#/definitions/Argument"
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}
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},
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"environmentVariables": {
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"type": "array",
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"description": "A mapping of environment variables to be set when running the package.",
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"items": {
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"$ref": "#/definitions/KeyValueInput"
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}
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}
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}
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},
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"Input": {
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"type": "object",
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"properties": {
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"description": {
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"description": "A description of the input, which clients can use to provide context to the user.",
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"type": "string"
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},
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"isRequired": {
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"type": "boolean",
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"default": false
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},
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"format": {
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"type": "string",
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"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.",
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"enum": [
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"string",
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"number",
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"boolean",
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"filepath"
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],
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"default": "string"
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},
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"value": {
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"type": "string",
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"description": "The 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"
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},
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"isSecret": {
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"type": "boolean",
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"description": "Indicates whether the input is a secret value (e.g., password, token). If true, clients should handle the value securely.",
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"default": false
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},
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"default": {
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"type": "string",
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"description": "The default value for the input. This should be a valid value for the input. If you want to provide input examples or guidance, use the `placeholder` field instead."
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},
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"placeholder": {
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"type": "string",
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"description": "A placeholder for the input to be displaying during configuration. This is used to provide examples or guidance about the expected form or content of the input."
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},
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"choices": {
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"type": "array",
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"description": "A list of possible values for the input. If provided, the user must select one of these values.",
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"items": {
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"type": "string"
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},
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"example": []
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}
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}
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},
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"InputWithVariables": {
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"allOf": [
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{
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"$ref": "#/definitions/Input"
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},
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{
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"type": "object",
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"properties": {
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"variables": {
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"type": "object",
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"description": "A map of variable names to their values. Keys in the input `value` that are wrapped in `{curly_braces}` will be replaced with the corresponding variable values.",
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"additionalProperties": {
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"$ref": "#/definitions/Input"
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}
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}
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}
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}
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]
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},
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"PositionalArgument": {
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"description": "A positional input is a value inserted verbatim into the command line.",
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"allOf": [
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{
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"$ref": "#/definitions/InputWithVariables"
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},
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{
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"type": "object",
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"required": [
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"type"
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],
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"properties": {
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"type": {
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"type": "string",
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"enum": [
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"positional"
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],
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"example": "positional"
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},
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"valueHint": {
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"type": "string",
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"description": "An identifier for the positional argument. It is not part of the command line. It may be used by client configuration as a label identifying the argument. It is also used to identify the value in transport URL variable substitution.",
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"example": "file_path"
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},
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"isRepeated": {
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"type": "boolean",
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"description": "Whether the argument can be repeated multiple times in the command line.",
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"default": false
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}
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},
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"anyOf": [
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{
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"required": [
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"valueHint"
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]
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},
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{
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"required": [
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"value"
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]
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}
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]
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}
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]
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},
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"NamedArgument": {
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"description": "A command-line `--flag {value}`.",
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"allOf": [
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{
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"$ref": "#/definitions/InputWithVariables"
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},
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{
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"type": "object",
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"required": [
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"type",
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"name"
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],
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"properties": {
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"type": {
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"type": "string",
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"enum": [
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"named"
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],
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"example": "named"
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},
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"name": {
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"type": "string",
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"description": "The flag name, including any leading dashes.",
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"example": "--port"
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},
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"isRepeated": {
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"type": "boolean",
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"description": "Whether the argument can be repeated multiple times.",
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"default": false
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}
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}
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}
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]
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},
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"KeyValueInput": {
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"allOf": [
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{
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"$ref": "#/definitions/InputWithVariables"
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},
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{
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"type": "object",
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"required": [
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"name"
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],
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"properties": {
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"name": {
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"type": "string",
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"description": "Name of the header or environment variable.",
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"example": "SOME_VARIABLE"
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}
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}
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}
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]
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},
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"Argument": {
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"description": "Warning: Arguments construct command-line parameters that may contain user-provided input. This creates potential command injection risks if clients execute commands in a shell environment. For example, a malicious argument value like ';rm -rf ~/Development' could execute dangerous commands. Clients should prefer non-shell execution methods (e.g., posix_spawn) when possible to eliminate injection risks entirely. Where not possible, clients should obtain consent from users or agents to run the resolved command before execution.",
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"anyOf": [
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{
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"$ref": "#/definitions/PositionalArgument"
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},
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{
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"$ref": "#/definitions/NamedArgument"
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}
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]
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},
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"StdioTransport": {
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"type": "object",
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"required": [
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"type"
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],
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"properties": {
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"type": {
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"type": "string",
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"enum": [
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"stdio"
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],
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"description": "Transport type",
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"example": "stdio"
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}
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}
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},
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"StreamableHttpTransport": {
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"type": "object",
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"required": [
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"type",
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"url"
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],
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"properties": {
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"type": {
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"type": "string",
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"enum": [
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"streamable-http"
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],
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"description": "Transport type",
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"example": "streamable-http"
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},
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"url": {
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"type": "string",
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"description": "URL template for the streamable-http transport. Variables in {curly_braces} reference argument valueHints, argument names, or environment variable names. After variable substitution, this should produce a valid URI.",
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"example": "https://api.example.com/mcp"
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},
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"headers": {
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"type": "array",
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"description": "HTTP headers to include",
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"items": {
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"$ref": "#/definitions/KeyValueInput"
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}
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}
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}
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},
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"SseTransport": {
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"type": "object",
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"required": [
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"type",
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"url"
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],
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"properties": {
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"type": {
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"type": "string",
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"enum": [
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"sse"
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],
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"description": "Transport type",
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"example": "sse"
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},
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"url": {
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"type": "string",
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"format": "uri",
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"description": "Server-Sent Events endpoint URL",
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"example": "https://mcp-fs.example.com/sse"
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},
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"headers": {
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"type": "array",
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"description": "HTTP headers to include",
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"items": {
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"$ref": "#/definitions/KeyValueInput"
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}
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}
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}
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},
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"ServerDetail": {
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"description": "Schema for a static representation of an MCP server. Used in various contexts related to discovery, installation, and configuration.",
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"type": "object",
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"required": [
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"name",
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"description",
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"version"
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],
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"properties": {
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"name": {
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"type": "string",
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"description": "Server name in reverse-DNS format. Must contain exactly one forward slash separating namespace from server name.",
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"example": "io.github.user/weather",
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"pattern": "^[a-zA-Z0-9.-]+/[a-zA-Z0-9._-]+$",
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"minLength": 3,
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"maxLength": 200
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},
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"description": {
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"type": "string",
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"description": "Clear human-readable explanation of server functionality. Should focus on capabilities, not implementation details.",
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"example": "MCP server providing weather data and forecasts via OpenWeatherMap API",
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"minLength": 1,
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"maxLength": 100
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},
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"title": {
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"type": "string",
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"description": "Optional human-readable title or display name for the MCP server. MCP subregistries or clients MAY choose to use this for display purposes.",
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"example": "Weather API",
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"minLength": 1,
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"maxLength": 100
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},
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"repository": {
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"$ref": "#/definitions/Repository",
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"description": "Optional repository metadata for the MCP server source code. Recommended for transparency and security inspection."
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},
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"version": {
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"type": "string",
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"maxLength": 255,
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"example": "1.0.2",
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"description": "Version string for this server. SHOULD follow semantic versioning (e.g., '1.0.2', '2.1.0-alpha'). Equivalent of Implementation.version in MCP specification. Non-semantic versions are allowed but may not sort predictably. Version ranges are rejected (e.g., '^1.2.3', '~1.2.3', '>=1.2.3', '1.x', '1.*')."
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},
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"websiteUrl": {
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"type": "string",
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"format": "uri",
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"description": "Optional URL to the server's homepage, documentation, or project website. This provides a central link for users to learn more about the server. Particularly useful when the server has custom installation instructions or setup requirements.",
|
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"example": "https://modelcontextprotocol.io/examples"
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},
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"$schema": {
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"type": "string",
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"format": "uri",
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"description": "JSON Schema URI for this server.json format",
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"example": "https://static.modelcontextprotocol.io/schemas/2025-09-29/server.schema.json"
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},
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"packages": {
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"type": "array",
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"items": {
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"$ref": "#/definitions/Package"
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}
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},
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"remotes": {
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"type": "array",
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"items": {
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"anyOf": [
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{
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"$ref": "#/definitions/StreamableHttpTransport"
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},
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{
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"$ref": "#/definitions/SseTransport"
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}
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]
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}
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},
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"_meta": {
|
|
"type": "object",
|
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"description": "Extension metadata using reverse DNS namespacing for vendor-specific data",
|
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"additionalProperties": true,
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"properties": {
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"io.modelcontextprotocol.registry/publisher-provided": {
|
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"type": "object",
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"description": "Publisher-provided metadata for downstream registries",
|
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"additionalProperties": true
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}
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}
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}
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}
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|
}
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}
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}
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