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Merged
alexhancock merged 8 commits into from
Sep 4, 2025
Merged

Spec conformance: meta support and spec updates #415

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2a7e60d
feat: add _meta to content blocks and embedded resources; update schemas
aharvard Sep 3, 2025
3180808
feat: set default protocol version; add _meta to content blocks/resou…
aharvard Sep 3, 2025
76d5533
chore: format content.rs via rustfmt
aharvard Sep 3, 2025
f021b00
chore(protocol): keep LATEST at 2025-03-26 per review until full 2025…
aharvard Sep 3, 2025
e9c8069
feat(prompt): add constructors with optional meta for image and resource
aharvard Sep 3, 2025
1af6906
refactor(prompt): simplify constructors so meta is optional; remove d…
aharvard Sep 3, 2025
c8ff500
fix: modify code comment about version
aharvard Sep 3, 2025
6ef61bb
refactor(prompt): rename meta parameters in new_resource function for…
aharvard Sep 4, 2025
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2 changes: 1 addition & 1 deletion crates/rmcp/src/model.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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aharvard marked this conversation as resolved.
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}

impl Serialize for ProtocolVersion {
Expand Down
18 changes: 9 additions & 9 deletions crates/rmcp/src/model/annotated.rs
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Expand Up @@ -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>>,

@aharvard aharvard Sep 3, 2025

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I was curious about this, I asked Goose, why did we change the timestamp to last_modified?

Short answer: to match the spec and be precise.

Details:

Spec alignment: The current MCP spec uses lastModified (camelCase on the wire) to mean “when this content/resource was last updated.” Our previous timestamp field was an SDK-ism and didn’t match the spec name.

Clearer semantics: timestamp was ambiguous (creation time? event time?); lastModified explicitly conveys modification time, which also aligns with common HTTP/metadata semantics.

Cross‑SDK consistency: Other SDKs and examples use lastModified, so this keeps the Rust SDK consistent.

Rust naming: In Rust we expose last_modified and serialize as lastModified to conform to the JSON field name.

}

impl Annotations {
Expand All @@ -30,7 +30,7 @@ impl Annotations {
);
Annotations {
priority: Some(priority),
timestamp: Some(timestamp),
last_modified: Some(timestamp),
audience: None,
}
}
Expand Down Expand Up @@ -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
Expand All @@ -92,7 +92,7 @@ impl<T: AnnotateAble> Annotated<T> {
annotations: Some(Annotations {
audience: Some(audience),
priority: None,
timestamp: None,
last_modified: None,
}),
}
}
Expand All @@ -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,
}),
}
Expand All @@ -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,
}),
Expand Down Expand Up @@ -211,7 +211,7 @@ pub trait AnnotateAble: sealed::Sealed {
Self: Sized,
{
self.annotate(Annotations {
timestamp: Some(timestamp),
last_modified: Some(timestamp),
..Default::default()
})
}
Expand Down
14 changes: 13 additions & 1 deletion crates/rmcp/src/model/content.rs
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Expand Up @@ -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)]
Expand All @@ -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,
Expand Down Expand Up @@ -79,13 +86,17 @@ 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,
})
}

Expand Down Expand Up @@ -209,6 +220,7 @@ 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();
Expand Down
23 changes: 23 additions & 0 deletions crates/rmcp/src/model/prompt.rs
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Expand Up @@ -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>>(

@alexhancock alexhancock Sep 3, 2025

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Seems like we should have ways to create each kind of prompt message with meta optionally supplied vs just this one type that has new_text and new_text_with_meta

@aharvard aharvard Sep 3, 2025

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ok, I think I've addressed this. LMK if me and Goose got it wrong, thanks!

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,
Expand All @@ -131,6 +152,7 @@ impl PromptMessage {
image: RawImageContent {
data: base64,
mime_type,
meta: None,
}
.optional_annotate(annotations),
},
Expand Down Expand Up @@ -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();
Expand Down
29 changes: 23 additions & 6 deletions crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json
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Expand Up @@ -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"
}
}
},
Expand Down Expand Up @@ -859,6 +859,7 @@
"type": "object",
"properties": {
"_meta": {
"description": "Optional protocol-level metadata for this content block",
"type": [
"object",
"null"
Expand All @@ -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"
Expand Down Expand Up @@ -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"
}
Expand Down
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