Use JsonElement.Parse for string-to-JsonElement deserialization (#1002)

Copilot · stephentoub · web-flow · commit a559bfb891c2 · 2025-11-21T11:00:11.000+02:00
Co-authored-by: copilot-swe-agent[bot] &lt;198982749+Copilot@users.noreply.github.com&gt;
Co-authored-by: stephentoub &lt;2642209+stephentoub@users.noreply.github.com&gt;
diff --git a/docs/concepts/elicitation/samples/client/Program.cs b/docs/concepts/elicitation/samples/client/Program.cs
@@ -78,16 +78,16 @@ async ValueTask<ElicitResult> HandleElicitationAsync(ElicitRequestParams? reques
             // Try standard boolean parsing first
             if (bool.TryParse(clientInput, out parsedBool))
             {
-                content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(parsedBool));
+                content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(parsedBool));
             }
             // Also accept "yes"/"no" as valid boolean inputs
             else if (string.Equals(clientInput?.Trim(), "yes", StringComparison.OrdinalIgnoreCase))
             {
-                content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(true));
+                content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(true));
             }
             else if (string.Equals(clientInput?.Trim(), "no", StringComparison.OrdinalIgnoreCase))
             {
-                content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(false));
+                content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(false));
             }
         }
         else if (property.Value is ElicitRequestParams.NumberSchema numberSchema)
@@ -97,14 +97,14 @@ async ValueTask<ElicitResult> HandleElicitationAsync(ElicitRequestParams? reques
             double parsedNumber;
             if (double.TryParse(clientInput, out parsedNumber))
             {
-                content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(parsedNumber));
+                content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(parsedNumber));
             }
         }
         else if (property.Value is ElicitRequestParams.StringSchema stringSchema)
         {
             Console.Write($"{stringSchema.Description}: ");
             var clientInput = Console.ReadLine();
-            content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(clientInput));
+            content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(clientInput));
         }
     }
 
diff --git a/tests/ModelContextProtocol.TestServer/Program.cs b/tests/ModelContextProtocol.TestServer/Program.cs
@@ -81,7 +81,7 @@ await server.SendMessageAsync(new JsonRpcNotification
                         Params = JsonSerializer.SerializeToNode(new LoggingMessageNotificationParams
                         {
                             Level = logLevel,
-                            Data = JsonSerializer.Deserialize<JsonElement>("\"Random log message\"")
+                            Data = JsonElement.Parse("\"Random log message\"")
                         })
                     }, cancellationToken);
                 }
@@ -117,7 +117,7 @@ private static void ConfigureTools(McpServerOptions options, string? cliArg)
                     {
                         Name = "echo",
                         Description = "Echoes the input back to the client.",
-                        InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                        InputSchema = JsonElement.Parse("""
                             {
                                 "type": "object",
                                 "properties": {
@@ -134,17 +134,17 @@ private static void ConfigureTools(McpServerOptions options, string? cliArg)
                     {
                         Name = "echoSessionId",
                         Description = "Echoes the session id back to the client.",
-                        InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                        InputSchema = JsonElement.Parse("""
                             {
                                 "type": "object"
                             }
-                            """, McpJsonUtilities.DefaultOptions),
+                            """),
                     },
                     new Tool
                     {
                         Name = "sampleLLM",
                         Description = "Samples from an LLM using MCP's sampling feature.",
-                        InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                        InputSchema = JsonElement.Parse("""
                             {
                                 "type": "object",
                                 "properties": {
diff --git a/tests/ModelContextProtocol.TestSseServer/Program.cs b/tests/ModelContextProtocol.TestSseServer/Program.cs
@@ -107,7 +107,7 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st
                         {
                             Name = "echo",
                             Description = "Echoes the input back to the client.",
-                            InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                            InputSchema = JsonElement.Parse("""
                                 {
                                     "type": "object",
                                     "properties": {
@@ -118,23 +118,23 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st
                                     },
                                     "required": ["message"]
                                 }
-                                """, McpJsonUtilities.DefaultOptions),
+                                """),
                         },
                         new Tool
                         {
                             Name = "echoSessionId",
                             Description = "Echoes the session id back to the client.",
-                            InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                            InputSchema = JsonElement.Parse("""
                                 {
                                     "type": "object"
                                 }
-                                """, McpJsonUtilities.DefaultOptions),
+                                """),
                         },
                         new Tool
                         {
                             Name = "sampleLLM",
                             Description = "Samples from an LLM using MCP's sampling feature.",
-                            InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                            InputSchema = JsonElement.Parse("""
                                 {
                                     "type": "object",
                                     "properties": {
@@ -149,7 +149,7 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st
                                     },
                                     "required": ["prompt", "maxTokens"]
                                 }
-                                """, McpJsonUtilities.DefaultOptions),
+                                """),
                         }
                     ]
                 };
diff --git a/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs b/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs
@@ -43,13 +43,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer
                                 {
                                     Name = "FirstCustomTool",
                                     Description = "First tool returned by custom handler",
-                                    InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                                    InputSchema = JsonElement.Parse("""
                                         {
                                           "type": "object",
                                           "properties": {},
                                           "required": []
                                         }
-                                        """, McpJsonUtilities.DefaultOptions),
+                                        """),
                                 }],
                         };
 
@@ -61,13 +61,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer
                                 {
                                     Name = "SecondCustomTool",
                                     Description = "Second tool returned by custom handler",
-                                    InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                                    InputSchema = JsonElement.Parse("""
                                         {
                                           "type": "object",
                                           "properties": {},
                                           "required": []
                                         }
-                                        """, McpJsonUtilities.DefaultOptions),
+                                        """),
                                 }],
                         };
 
@@ -79,13 +79,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer
                                 {
                                     Name = "FinalCustomTool",
                                     Description = "Third tool returned by custom handler",
-                                    InputSchema = JsonSerializer.Deserialize<JsonElement>("""
+                                    InputSchema = JsonElement.Parse("""
                                         {
                                           "type": "object",
                                           "properties": {},
                                           "required": []
                                         }
-                                        """, McpJsonUtilities.DefaultOptions),
+                                        """),
                                 }],
                         };
 
diff --git a/tests/ModelContextProtocol.Tests/Protocol/ElicitationTests.cs b/tests/ModelContextProtocol.Tests/Protocol/ElicitationTests.cs
@@ -120,18 +120,18 @@ public async Task Can_Elicit_Information()
                         Action = "accept",
                         Content = new Dictionary<string, JsonElement>
                         {
-                            ["prop1"] = (JsonElement)JsonSerializer.Deserialize("""
+                            ["prop1"] = JsonElement.Parse("""
                                 "string result"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            ["prop2"] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            ["prop2"] = JsonElement.Parse("""
                                 42
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            ["prop3"] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            ["prop3"] = JsonElement.Parse("""
                                 true
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            ["prop4"] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            ["prop4"] = JsonElement.Parse("""
                                 "option2"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
+                                """),
                         },
                     };
                 }
diff --git a/tests/ModelContextProtocol.Tests/Protocol/ElicitationTypedTests.cs b/tests/ModelContextProtocol.Tests/Protocol/ElicitationTypedTests.cs
@@ -177,24 +177,24 @@ public async Task Can_Elicit_Typed_Information()
                         Action = "accept",
                         Content = new Dictionary<string, JsonElement>
                         {
-                            [nameof(SampleForm.Name)] = (JsonElement)JsonSerializer.Deserialize("""
+                            [nameof(SampleForm.Name)] = JsonElement.Parse("""
                                 "Alice"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            [nameof(SampleForm.Age)] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            [nameof(SampleForm.Age)] = JsonElement.Parse("""
                                 30
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            [nameof(SampleForm.Active)] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            [nameof(SampleForm.Active)] = JsonElement.Parse("""
                                 true
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            [nameof(SampleForm.Role)] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            [nameof(SampleForm.Role)] = JsonElement.Parse("""
                                 "Admin"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            [nameof(SampleForm.Score)] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            [nameof(SampleForm.Score)] = JsonElement.Parse("""
                                 99.5
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            [nameof(SampleForm.Created)] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            [nameof(SampleForm.Created)] = JsonElement.Parse("""
                                 "2023-08-27T03:05:00"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
+                                """),
                         },
                     };
                 },
@@ -228,15 +228,15 @@ public async Task Elicit_Typed_Respects_NamingPolicy()
                         Action = "accept",
                         Content = new Dictionary<string, JsonElement>
                         {
-                            ["firstName"] = (JsonElement)JsonSerializer.Deserialize("""
+                            ["firstName"] = JsonElement.Parse("""
                                 "Bob"
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            ["zipCode"] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            ["zipCode"] = JsonElement.Parse("""
                                 90210
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
-                            ["isAdmin"] = (JsonElement)JsonSerializer.Deserialize("""
+                                """),
+                            ["isAdmin"] = JsonElement.Parse("""
                                 false
-                                """, McpJsonUtilities.DefaultOptions.GetTypeInfo(typeof(JsonElement)))!,
+                                """),
                         },
                     };
                 },

Original file line number	Diff line number	Diff line change
`@@ -78,16 +78,16 @@ async ValueTask<ElicitResult> HandleElicitationAsync(ElicitRequestParams? reques`
`78`	`78`	`// Try standard boolean parsing first`
`79`	`79`	`if (bool.TryParse(clientInput, out parsedBool))`
`80`	`80`	`{`
`81`		`- content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(parsedBool));`
	`81`	`+ content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(parsedBool));`
`82`	`82`	`}`
`83`	`83`	`// Also accept "yes"/"no" as valid boolean inputs`
`84`	`84`	`else if (string.Equals(clientInput?.Trim(), "yes", StringComparison.OrdinalIgnoreCase))`
`85`	`85`	`{`
`86`		`- content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(true));`
	`86`	`+ content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(true));`
`87`	`87`	`}`
`88`	`88`	`else if (string.Equals(clientInput?.Trim(), "no", StringComparison.OrdinalIgnoreCase))`
`89`	`89`	`{`
`90`		`- content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(false));`
	`90`	`+ content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(false));`
`91`	`91`	`}`
`92`	`92`	`}`
`93`	`93`	`else if (property.Value is ElicitRequestParams.NumberSchema numberSchema)`
`@@ -97,14 +97,14 @@ async ValueTask<ElicitResult> HandleElicitationAsync(ElicitRequestParams? reques`
`97`	`97`	`double parsedNumber;`
`98`	`98`	`if (double.TryParse(clientInput, out parsedNumber))`
`99`	`99`	`{`
`100`		`- content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(parsedNumber));`
	`100`	`+ content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(parsedNumber));`
`101`	`101`	`}`
`102`	`102`	`}`
`103`	`103`	`else if (property.Value is ElicitRequestParams.StringSchema stringSchema)`
`104`	`104`	`{`
`105`	`105`	`Console.Write($"{stringSchema.Description}: ");`
`106`	`106`	`var clientInput = Console.ReadLine();`
`107`		`- content[property.Key] = JsonSerializer.Deserialize<JsonElement>(JsonSerializer.Serialize(clientInput));`
	`107`	`+ content[property.Key] = JsonElement.Parse(JsonSerializer.Serialize(clientInput));`
`108`	`108`	`}`
`109`	`109`	`}`
`110`	`110`
Original file line number	Diff line number	Diff line change
`@@ -81,7 +81,7 @@ await server.SendMessageAsync(new JsonRpcNotification`
`81`	`81`	`Params = JsonSerializer.SerializeToNode(new LoggingMessageNotificationParams`
`82`	`82`	`{`
`83`	`83`	`Level = logLevel,`
`84`		`- Data = JsonSerializer.Deserialize<JsonElement>("\"Random log message\"")`
	`84`	`+ Data = JsonElement.Parse("\"Random log message\"")`
`85`	`85`	`})`
`86`	`86`	`}, cancellationToken);`
`87`	`87`	`}`
`@@ -117,7 +117,7 @@ private static void ConfigureTools(McpServerOptions options, string? cliArg)`
`117`	`117`	`{`
`118`	`118`	`Name = "echo",`
`119`	`119`	`Description = "Echoes the input back to the client.",`
`120`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`120`	`+ InputSchema = JsonElement.Parse("""`
`121`	`121`	`{`
`122`	`122`	`"type": "object",`
`123`	`123`	`"properties": {`
`@@ -134,17 +134,17 @@ private static void ConfigureTools(McpServerOptions options, string? cliArg)`
`134`	`134`	`{`
`135`	`135`	`Name = "echoSessionId",`
`136`	`136`	`Description = "Echoes the session id back to the client.",`
`137`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`137`	`+ InputSchema = JsonElement.Parse("""`
`138`	`138`	`{`
`139`	`139`	`"type": "object"`
`140`	`140`	`}`
`141`		`- """, McpJsonUtilities.DefaultOptions),`
	`141`	`+ """),`
`142`	`142`	`},`
`143`	`143`	`new Tool`
`144`	`144`	`{`
`145`	`145`	`Name = "sampleLLM",`
`146`	`146`	`Description = "Samples from an LLM using MCP's sampling feature.",`
`147`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`147`	`+ InputSchema = JsonElement.Parse("""`
`148`	`148`	`{`
`149`	`149`	`"type": "object",`
`150`	`150`	`"properties": {`
Original file line number	Diff line number	Diff line change
`@@ -107,7 +107,7 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st`
`107`	`107`	`{`
`108`	`108`	`Name = "echo",`
`109`	`109`	`Description = "Echoes the input back to the client.",`
`110`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`110`	`+ InputSchema = JsonElement.Parse("""`
`111`	`111`	`{`
`112`	`112`	`"type": "object",`
`113`	`113`	`"properties": {`
`@@ -118,23 +118,23 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st`
`118`	`118`	`},`
`119`	`119`	`"required": ["message"]`
`120`	`120`	`}`
`121`		`- """, McpJsonUtilities.DefaultOptions),`
	`121`	`+ """),`
`122`	`122`	`},`
`123`	`123`	`new Tool`
`124`	`124`	`{`
`125`	`125`	`Name = "echoSessionId",`
`126`	`126`	`Description = "Echoes the session id back to the client.",`
`127`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`127`	`+ InputSchema = JsonElement.Parse("""`
`128`	`128`	`{`
`129`	`129`	`"type": "object"`
`130`	`130`	`}`
`131`		`- """, McpJsonUtilities.DefaultOptions),`
	`131`	`+ """),`
`132`	`132`	`},`
`133`	`133`	`new Tool`
`134`	`134`	`{`
`135`	`135`	`Name = "sampleLLM",`
`136`	`136`	`Description = "Samples from an LLM using MCP's sampling feature.",`
`137`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`137`	`+ InputSchema = JsonElement.Parse("""`
`138`	`138`	`{`
`139`	`139`	`"type": "object",`
`140`	`140`	`"properties": {`
`@@ -149,7 +149,7 @@ static CreateMessageRequestParams CreateRequestSamplingParams(string context, st`
`149`	`149`	`},`
`150`	`150`	`"required": ["prompt", "maxTokens"]`
`151`	`151`	`}`
`152`		`- """, McpJsonUtilities.DefaultOptions),`
	`152`	`+ """),`
`153`	`153`	`}`
`154`	`154`	`]`
`155`	`155`	`};`
Original file line number	Diff line number	Diff line change
`@@ -43,13 +43,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer`
`43`	`43`	`{`
`44`	`44`	`Name = "FirstCustomTool",`
`45`	`45`	`Description = "First tool returned by custom handler",`
`46`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`46`	`+ InputSchema = JsonElement.Parse("""`
`47`	`47`	`{`
`48`	`48`	`"type": "object",`
`49`	`49`	`"properties": {},`
`50`	`50`	`"required": []`
`51`	`51`	`}`
`52`		`- """, McpJsonUtilities.DefaultOptions),`
	`52`	`+ """),`
`53`	`53`	`}],`
`54`	`54`	`};`
`55`	`55`
`@@ -61,13 +61,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer`
`61`	`61`	`{`
`62`	`62`	`Name = "SecondCustomTool",`
`63`	`63`	`Description = "Second tool returned by custom handler",`
`64`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`64`	`+ InputSchema = JsonElement.Parse("""`
`65`	`65`	`{`
`66`	`66`	`"type": "object",`
`67`	`67`	`"properties": {},`
`68`	`68`	`"required": []`
`69`	`69`	`}`
`70`		`- """, McpJsonUtilities.DefaultOptions),`
	`70`	`+ """),`
`71`	`71`	`}],`
`72`	`72`	`};`
`73`	`73`
`@@ -79,13 +79,13 @@ protected override void ConfigureServices(ServiceCollection services, IMcpServer`
`79`	`79`	`{`
`80`	`80`	`Name = "FinalCustomTool",`
`81`	`81`	`Description = "Third tool returned by custom handler",`
`82`		`- InputSchema = JsonSerializer.Deserialize<JsonElement>("""`
	`82`	`+ InputSchema = JsonElement.Parse("""`
`83`	`83`	`{`
`84`	`84`	`"type": "object",`
`85`	`85`	`"properties": {},`
`86`	`86`	`"required": []`
`87`	`87`	`}`
`88`		`- """, McpJsonUtilities.DefaultOptions),`
	`88`	`+ """),`
`89`	`89`	`}],`
`90`	`90`	`};`
`91`	`91`