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[MCP Apps] Add appCapabilities.availableDisplayModes documentation to spec (#331)

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* Add appCapabilities.availableDisplayModes documentation to spec

Document the availableDisplayModes field in McpUiAppCapabilities that allows
apps to declare which display modes they support. This enables hosts to
compute the intersection of host and app capabilities and only offer
appropriate display mode controls.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Address PR review feedback

- Change "Guest UI" to "View" terminology
- Add "View" prefix to availableDisplayModes heading for disambiguation
- Remove intersection logic - host only checks its own supported modes
- Remove assumption that apps must support inline mode
- Simplify host behavior to honor/reject based on its own capabilities

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Add appCapabilities.availableDisplayModes to types

- Add `availableDisplayModes` field to `McpUiAppCapabilities` so apps can
  declare which display modes they support
- Change `HostContext.availableDisplayModes` type from `string[]` to
  `McpUiDisplayMode[]` for type safety
- Regenerate schemas

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Address Olivier's feedback - consolidate display mode docs

- Remove separate "App Capabilities" section for availableDisplayModes
- Add display mode requirements to existing ui/request-display-mode section:
  - Host MUST NOT switch View to mode not in appCapabilities.availableDisplayModes
  - Host MAY decline requests from Views that didn't declare modes
  - View MUST declare supported modes during initialization

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Co-Authored-By: Claude <noreply@anthropic.com>

* Restore McpUiAppCapabilities docs and fix display mode clause

- Restore McpUiAppCapabilities interface documentation with availableDisplayModes
- Restore "View MUST check if the requested mode is in availableDisplayModes
  from host context" clause that was accidentally removed

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Create unified Display Modes section

Consolidate all display mode documentation into a single section:
- Display mode types (inline, fullscreen, pip)
- Declaring support from View (appCapabilities.availableDisplayModes)
- Declaring support from Host (HostContext.availableDisplayModes)
- Requesting changes (ui/request-display-mode)
- Notifying changes (ui/notifications/host-context-changed)
- All MUST/SHOULD requirements for View and Host behavior

The ui/request-display-mode in Requests section now references
the Display Modes section for behavior details.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Remove mode coercion clause from display modes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Regenerate schemas with correct version

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Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
martinalong 2026-01-23 13:13:26 -08:00 • committed by GitHub
commit 89f58bf555
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3 changed files with 174 additions and 14 deletions
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90
src/generated/schema.json generated
View file

@ -24,6 +24,27 @@
}
},
"additionalProperties": false
},
"availableDisplayModes": {
"description": "Display modes the app supports.",
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"const": "inline"
},
{
"type": "string",
"const": "fullscreen"
},
{
"type": "string",
"const": "pip"
}
],
"description": "Display mode for UI presentation."
}
}
},
"additionalProperties": false
@ -882,7 +903,21 @@
"description": "Display modes the host supports.",
"type": "array",
"items": {
"type": "string"
"anyOf": [
{
"type": "string",
"const": "inline"
},
{
"type": "string",
"const": "fullscreen"
},
{
"type": "string",
"const": "pip"
}
],
"description": "Display mode for UI presentation."
}
},
"containerDimensions": {
@ -1635,7 +1670,21 @@
"description": "Display modes the host supports.",
"type": "array",
"items": {
"type": "string"
"anyOf": [
{
"type": "string",
"const": "inline"
},
{
"type": "string",
"const": "fullscreen"
},
{
"type": "string",
"const": "pip"
}
],
"description": "Display mode for UI presentation."
}
},
"containerDimensions": {
@ -2284,6 +2333,27 @@
}
},
"additionalProperties": false
},
"availableDisplayModes": {
"description": "Display modes the app supports.",
"type": "array",
"items": {
"anyOf": [
{
"type": "string",
"const": "inline"
},
{
"type": "string",
"const": "fullscreen"
},
{
"type": "string",
"const": "pip"
}
],
"description": "Display mode for UI presentation."
}
}
},
"additionalProperties": false,
@ -3172,7 +3242,21 @@
"description": "Display modes the host supports.",
"type": "array",
"items": {
"type": "string"
"anyOf": [
{
"type": "string",
"const": "inline"
},
{
"type": "string",
"const": "fullscreen"
},
{
"type": "string",
"const": "pip"
}
],
"description": "Display mode for UI presentation."
}
},
"containerDimensions": {

7
src/generated/schema.ts generated
View file

@ -470,6 +470,11 @@ export const McpUiAppCapabilitiesSchema = z.object({
})
.optional()
.describe("App exposes MCP-style tools that the host can call."),
/** @description Display modes the app supports. */
availableDisplayModes: z
.array(McpUiDisplayModeSchema)
.optional()
.describe("Display modes the app supports."),
});
/**
@ -668,7 +673,7 @@ export const McpUiHostContextSchema = z
),
/** @description Display modes the host supports. */
availableDisplayModes: z
.array(z.string())
.array(McpUiDisplayModeSchema)
.optional()
.describe("Display modes the host supports."),
/**

4
src/spec.types.ts
View file

@ -321,7 +321,7 @@ export interface McpUiHostContext {
/** @description How the UI is currently displayed. */
displayMode?: McpUiDisplayMode;
/** @description Display modes the host supports. */
availableDisplayModes?: string[];
availableDisplayModes?: McpUiDisplayMode[];
/**
* @description Container dimensions. Represents the dimensions of the iframe or other
* container holding the app. Specify either width or maxWidth, and either height or maxHeight.
@ -487,6 +487,8 @@ export interface McpUiAppCapabilities {
/** @description App supports tools/list_changed notifications. */
listChanged?: boolean;
};
/** @description Display modes the app supports. */
availableDisplayModes?: McpUiDisplayMode[];
}
/**