Spec conformance: meta support and spec updates

crates/rmcp/src/model.rs

@@ -149,7 +149,7 @@ impl ProtocolVersion {
     pub const V_2025_06_18: Self = Self(Cow::Borrowed("2025-06-18"));
     pub const V_2025_03_26: Self = Self(Cow::Borrowed("2025-03-26"));
     pub const V_2024_11_05: Self = Self(Cow::Borrowed("2024-11-05"));
-    pub const LATEST: Self = Self::V_2025_03_26;
+    pub const LATEST: Self = Self::V_2025_06_18;
 }
 
 impl Serialize for ProtocolVersion {

crates/rmcp/src/model/annotated.rs

@@ -16,8 +16,8 @@ pub struct Annotations {
     pub audience: Option<Vec<Role>>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub priority: Option<f32>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub timestamp: Option<DateTime<Utc>>,
+    #[serde(skip_serializing_if = "Option::is_none", rename = "lastModified")]
+    pub last_modified: Option<DateTime<Utc>>,
 }
 
 impl Annotations {
@@ -30,7 +30,7 @@ impl Annotations {
         );
         Annotations {
             priority: Some(priority),
-            timestamp: Some(timestamp),
+            last_modified: Some(timestamp),
             audience: None,
         }
     }
@@ -72,7 +72,7 @@ impl<T: AnnotateAble> Annotated<T> {
         self.annotations.as_ref().and_then(|a| a.priority)
     }
     pub fn timestamp(&self) -> Option<DateTime<Utc>> {
-        self.annotations.as_ref().and_then(|a| a.timestamp)
+        self.annotations.as_ref().and_then(|a| a.last_modified)
     }
     pub fn with_audience(self, audience: Vec<Role>) -> Annotated<T>
     where
@@ -92,7 +92,7 @@ impl<T: AnnotateAble> Annotated<T> {
                 annotations: Some(Annotations {
                     audience: Some(audience),
                     priority: None,
-                    timestamp: None,
+                    last_modified: None,
                 }),
             }
         }
@@ -114,7 +114,7 @@ impl<T: AnnotateAble> Annotated<T> {
                 raw: self.raw,
                 annotations: Some(Annotations {
                     priority: Some(priority),
-                    timestamp: None,
+                    last_modified: None,
                     audience: None,
                 }),
             }
@@ -128,15 +128,15 @@ impl<T: AnnotateAble> Annotated<T> {
             Annotated {
                 raw: self.raw,
                 annotations: Some(Annotations {
-                    timestamp: Some(timestamp),
+                    last_modified: Some(timestamp),
                     ..annotations
                 }),
             }
         } else {
             Annotated {
                 raw: self.raw,
                 annotations: Some(Annotations {
-                    timestamp: Some(timestamp),
+                    last_modified: Some(timestamp),
                     priority: None,
                     audience: None,
                 }),
@@ -211,7 +211,7 @@ pub trait AnnotateAble: sealed::Sealed {
         Self: Sized,
     {
         self.annotate(Annotations {
-            timestamp: Some(timestamp),
+            last_modified: Some(timestamp),
             ..Default::default()
         })
     }

crates/rmcp/src/model/content.rs

@@ -11,6 +11,9 @@ use super::{AnnotateAble, Annotated, resource::ResourceContents};
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct RawTextContent {
     pub text: String,
+    /// Optional protocol-level metadata for this content block
+    #[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
+    pub meta: Option<super::Meta>,
 }
 pub type TextContent = Annotated<RawTextContent>;
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
@@ -20,13 +23,17 @@ pub struct RawImageContent {
     /// The base64-encoded image
     pub data: String,
     pub mime_type: String,
+    /// Optional protocol-level metadata for this content block
+    #[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
+    pub meta: Option<super::Meta>,
 }
 
 pub type ImageContent = Annotated<RawImageContent>;
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct RawEmbeddedResource {
+    /// Optional protocol-level metadata for this content block
     #[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
     pub meta: Option<super::Meta>,
     pub resource: ResourceContents,
@@ -79,13 +86,14 @@ impl RawContent {
     }
 
     pub fn text<S: Into<String>>(text: S) -> Self {
-        RawContent::Text(RawTextContent { text: text.into() })
+        RawContent::Text(RawTextContent { text: text.into(), meta: None })
     }
 
     pub fn image<S: Into<String>, T: Into<String>>(data: S, mime_type: T) -> Self {
         RawContent::Image(RawImageContent {
             data: data.into(),
             mime_type: mime_type.into(),
+            meta: None,
         })
     }
 
@@ -209,6 +217,7 @@ mod tests {
         let image_content = RawImageContent {
             data: "base64data".to_string(),
             mime_type: "image/png".to_string(),
+            meta: None,
         };
 
         let json = serde_json::to_string(&image_content).unwrap();

crates/rmcp/src/model/prompt.rs

@@ -114,6 +114,27 @@ impl PromptMessage {
             content: PromptMessageContent::Text { text: text.into() },
         }
     }
+
+    /// Create a new text message with meta
+    pub fn new_text_with_meta<S: Into<String>>(
+        role: PromptMessageRole,
+        text: S,
+        meta: Option<crate::model::Meta>,
+    ) -> Self {
+        use crate::model::{AnnotateAble, RawTextContent};
+        let annotated = RawTextContent {
+            text: text.into(),
+            meta,
+        }
+        .no_annotation();
+        // Map into Content using same tagging as PromptMessageContent::Text
+        Self {
+            role,
+            content: PromptMessageContent::Text {
+                text: annotated.raw.text,
+            },
+        }
+    }
     #[cfg(feature = "base64")]
     pub fn new_image(
         role: PromptMessageRole,
@@ -131,6 +152,7 @@ impl PromptMessage {
                 image: RawImageContent {
                     data: base64,
                     mime_type,
+                    meta: None,
                 }
                 .optional_annotate(annotations),
             },
@@ -184,6 +206,7 @@ mod tests {
         let image_content = RawImageContent {
             data: "base64data".to_string(),
             mime_type: "image/png".to_string(),
+            meta: None,
         };
 
         let json = serde_json::to_string(&image_content).unwrap();

crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json

@@ -176,19 +176,19 @@
             "$ref": "#/definitions/Role"
           }
         },
-        "priority": {
+        "lastModified": {
           "type": [
-            "number",
+            "string",
             "null"
           ],
-          "format": "float"
+          "format": "date-time"
         },
-        "timestamp": {
+        "priority": {
           "type": [
-            "string",
+            "number",
             "null"
           ],
-          "format": "date-time"
+          "format": "float"
         }
       }
     },
@@ -859,6 +859,7 @@
       "type": "object",
       "properties": {
         "_meta": {
+          "description": "Optional protocol-level metadata for this content block",
           "type": [
             "object",
             "null"
@@ -876,6 +877,14 @@
     "RawImageContent": {
       "type": "object",
       "properties": {
+        "_meta": {
+          "description": "Optional protocol-level metadata for this content block",
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
         "data": {
           "description": "The base64-encoded image",
           "type": "string"
@@ -933,6 +942,14 @@
     "RawTextContent": {
       "type": "object",
       "properties": {
+        "_meta": {
+          "description": "Optional protocol-level metadata for this content block",
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
         "text": {
           "type": "string"
         }