feat: expose MCP tool annotations for tool grouping (#23195)

## Summary
- add shared MCP annotation metadata to toolsdk tools
- emit MCP tool annotations from both coderd and CLI MCP servers
- cover annotation serialization in toolsdk, coderd MCP e2e, and CLI MCP
tests

## Why
- Coder already exposed MCP tools, but it did not populate MCP tool
annotation hints (`readOnlyHint`, `destructiveHint`, `idempotentHint`,
`openWorldHint`).
- Hosts such as Claude Desktop use those hints to classify and group
tools, so without them Coder tools can get lumped together.
- This change adds a shared annotation source in `toolsdk` and has both
MCP servers emit those hints through `mcp.Tool.Annotations`, avoiding
drift between local and remote MCP implementations.

## Testing
- Tested locally on Cladue Desktop and the tools are categorized
correctly.

<table>
<tr>
 <td> Before
 <td> After
<tr>
<td> <img width="613" height="183" alt="image"
src="https://github.com/user-attachments/assets/29d2e3fb-53bc-4ea7-bdb3-f10df4ef996b"
/>
<td> <img width="600" height="457" alt="image"
src="https://github.com/user-attachments/assets/cc384036-c9a7-4db9-9400-43ad51920ff5"
/>
</table>

Note: Done using Coder Agents, reviewed and tested by human locally

coderd/mcp/mcp.go

@@ -136,6 +136,12 @@ func mcpFromSDK(sdkTool toolsdk.GenericTool, tb toolsdk.Deps) server.ServerTool
 				Properties: sdkTool.Schema.Properties,
 				Required:   sdkTool.Schema.Required,
 			},
+			Annotations: mcp.ToolAnnotation{
+				ReadOnlyHint:    mcp.ToBoolPtr(sdkTool.MCPAnnotations.ReadOnlyHint),
+				DestructiveHint: mcp.ToBoolPtr(sdkTool.MCPAnnotations.DestructiveHint),
+				IdempotentHint:  mcp.ToBoolPtr(sdkTool.MCPAnnotations.IdempotentHint),
+				OpenWorldHint:   mcp.ToBoolPtr(sdkTool.MCPAnnotations.OpenWorldHint),
+			},
 		},
 		Handler: func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 			var buf bytes.Buffer

coderd/mcp/mcp_e2e_test.go

@@ -91,21 +91,41 @@ func TestMCPHTTP_E2E_ClientIntegration(t *testing.T) {
 
 	// Verify we have some expected Coder tools
 	var foundTools []string
-	for _, tool := range tools.Tools {
+	var userTool *mcp.Tool
+	var writeFileTool *mcp.Tool
+	for i := range tools.Tools {
+		tool := tools.Tools[i]
 		foundTools = append(foundTools, tool.Name)
+		switch tool.Name {
+		case toolsdk.ToolNameGetAuthenticatedUser:
+			userTool = &tools.Tools[i]
+		case toolsdk.ToolNameWorkspaceWriteFile:
+			writeFileTool = &tools.Tools[i]
+		}
 	}
 
 	// Check for some basic tools that should be available
 	assert.Contains(t, foundTools, toolsdk.ToolNameGetAuthenticatedUser, "Should have authenticated user tool")
+	require.NotNil(t, userTool)
+	require.NotNil(t, writeFileTool)
+	require.NotNil(t, userTool.Annotations.ReadOnlyHint)
+	require.NotNil(t, userTool.Annotations.DestructiveHint)
+	require.NotNil(t, userTool.Annotations.IdempotentHint)
+	require.NotNil(t, userTool.Annotations.OpenWorldHint)
+	assert.True(t, *userTool.Annotations.ReadOnlyHint)
+	assert.False(t, *userTool.Annotations.DestructiveHint)
+	assert.True(t, *userTool.Annotations.IdempotentHint)
+	assert.False(t, *userTool.Annotations.OpenWorldHint)
+	require.NotNil(t, writeFileTool.Annotations.ReadOnlyHint)
+	require.NotNil(t, writeFileTool.Annotations.DestructiveHint)
+	require.NotNil(t, writeFileTool.Annotations.IdempotentHint)
+	require.NotNil(t, writeFileTool.Annotations.OpenWorldHint)
+	assert.False(t, *writeFileTool.Annotations.ReadOnlyHint)
+	assert.True(t, *writeFileTool.Annotations.DestructiveHint)
+	assert.False(t, *writeFileTool.Annotations.IdempotentHint)
+	assert.False(t, *writeFileTool.Annotations.OpenWorldHint)
 
-	// Find and execute the authenticated user tool
-	var userTool *mcp.Tool
-	for _, tool := range tools.Tools {
-		if tool.Name == toolsdk.ToolNameGetAuthenticatedUser {
-			userTool = &tool
-			break
-		}
-	}
+	// Execute the authenticated user tool.
 	require.NotNil(t, userTool, "Expected to find "+toolsdk.ToolNameGetAuthenticatedUser+" tool")
 
 	// Execute the tool