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Complete JSON-RPC message examples in Data Passing section

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The tool input and tool result examples now show fully formed JSON-RPC
messages with all required fields (jsonrpc, id/method, result/params) to
better demonstrate the protocol format. Also fixes MDX parsing error in
Client\<>Server heading by escaping angle brackets.

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

Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Jonathan Hefner 2025-11-21 16:04:52 -06:00
commit cc08467772
1 changed files with 56 additions and 25 deletions
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81
specification/draft/apps.mdx
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@ -751,13 +751,28 @@ Tool execution results are passed to the UI through two mechanisms:
The original tool call arguments:
```typescript
// Tool was called with:
tools/call("get_weather", { location: "San Francisco" })
// Tool was called with (JSON-RPC request from Host to Server):
{
jsonrpc: "2.0",
id: 1,
method: "tools/call",
params: {
name: "get_weather",
arguments: {
location: "San Francisco"
}
}
}
// UI receives:
notification: ui/notifications/tool-input
params: {
arguments: { location: "San Francisco" }
// UI receives (JSON-RPC notification from Host to UI):
{
jsonrpc: "2.0",
method: "ui/notifications/tool-input",
params: {
arguments: {
location: "San Francisco"
}
}
}
```
@ -766,28 +781,44 @@ params: {
The tool's execution result:
```typescript
// Server returns from tool execution:
// Server returns from tool execution (JSON-RPC response):
{
content: [
{ type: "text", text: "Current weather: Sunny, 72°F" }
],
structuredContent: {
temperature: 72,
conditions: "sunny",
humidity: 45
},
_meta: {
timestamp: "2025-11-10T15:30:00Z",
source: "weather-api"
jsonrpc: "2.0",
id: 1, // Matches the tools/call request id
result: {
content: [
{ type: "text", text: "Current weather: Sunny, 72°F" }
],
structuredContent: {
temperature: 72,
conditions: "sunny",
humidity: 45
},
_meta: {
timestamp: "2025-11-10T15:30:00Z",
source: "weather-api"
}
}
}
// UI receives:
Notification: ui/notifications/tool-result
params: {
content: [...], // Same as above
structuredContent: { temperature: 72, ... },
_meta: { timestamp: "...", ... }
// UI receives (JSON-RPC notification):
{
jsonrpc: "2.0",
method: "ui/notifications/tool-result",
params: {
content: [
{ type: "text", text: "Current weather: Sunny, 72°F" }
],
structuredContent: {
temperature: 72,
conditions: "sunny",
humidity: 45
},
_meta: {
timestamp: "2025-11-10T15:30:00Z",
source: "weather-api"
}
}
}
```
@ -812,7 +843,7 @@ This pattern enables interactive, self-updating widgets.
Note: The called tool may not appear in `tools/list` responses. MCP servers MAY expose private tools specifically designed for UI interaction that are not visible to the agent. UI implementations SHOULD attempt to call tools by name regardless of discoverability. The specification for Private Tools will be covered in a future SEP.
### Client<>Server Capability Negotiation
### Client\<\>Server Capability Negotiation
Clients and servers negotiate MCP Apps support through the standard MCP extensions capability mechanism (defined in SEP-1724).