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Added _meta field to prompts, resources and paginated results #558

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423ede0
Added _meta field to prompts, resources and paginated result
pbezglasny Nov 24, 2025
140be55
Update crates/rmcp-macros/src/prompt_handler.rs
pbezglasny Nov 24, 2025
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11 changes: 11 additions & 0 deletions crates/rmcp-macros/src/prompt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@ pub struct PromptAttribute {
pub arguments: Option<Expr>,
/// Optional icons for the prompt
pub icons: Option<Expr>,
/// Optional metadata for the prompt
pub meta: Option<Expr>,
}

pub struct ResolvedPromptAttribute {
Expand All @@ -26,6 +28,7 @@ pub struct ResolvedPromptAttribute {
pub description: Option<Expr>,
pub arguments: Expr,
pub icons: Option<Expr>,
pub meta: Option<Expr>,
}

impl ResolvedPromptAttribute {
Expand All @@ -36,6 +39,7 @@ impl ResolvedPromptAttribute {
arguments,
title,
icons,
meta,
} = self;
let description = if let Some(description) = description {
quote! { Some(#description.into()) }
Expand All @@ -52,6 +56,11 @@ impl ResolvedPromptAttribute {
} else {
quote! { None }
};
let meta = if let Some(meta) = meta {
quote! { Some(#meta) }
} else {
quote! { None }
};
let tokens = quote! {
pub fn #fn_ident() -> rmcp::model::Prompt {
rmcp::model::Prompt {
Expand All @@ -60,6 +69,7 @@ impl ResolvedPromptAttribute {
arguments: #arguments,
title: #title,
icons: #icons,
meta: #meta,
}
}
};
Expand Down Expand Up @@ -114,6 +124,7 @@ pub fn prompt(attr: TokenStream, input: TokenStream) -> syn::Result<TokenStream>
arguments: arguments.clone(),
title: attribute.title,
icons: attribute.icons,
meta: attribute.meta,
};
let prompt_attr_fn = resolved_prompt_attr.into_fn(prompt_attr_fn_ident.clone())?;

Expand Down
10 changes: 9 additions & 1 deletion crates/rmcp-macros/src/prompt_handler.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ use syn::{Expr, ImplItem, ItemImpl, parse_quote};
#[darling(default)]
pub struct PromptHandlerAttribute {
pub router: Option<Expr>,
pub meta: Option<Expr>,
}

pub fn prompt_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenStream> {
Expand Down Expand Up @@ -40,6 +41,12 @@ pub fn prompt_handler(attr: TokenStream, input: TokenStream) -> syn::Result<Toke
}
};

let meta = if let Some(meta) = attribute.meta {
quote! { Some(#meta) }
} else {
quote! { None }
};

// Add list_prompts implementation
let list_prompts_impl: ImplItem = parse_quote! {
async fn list_prompts(
Expand All @@ -50,7 +57,8 @@ pub fn prompt_handler(attr: TokenStream, input: TokenStream) -> syn::Result<Toke
let prompts = #router_expr.list_all();
Ok(ListPromptsResult {
prompts,
next_cursor: None,
meta: #meta,
next_cursor: None
})
}
};
Expand Down
17 changes: 15 additions & 2 deletions crates/rmcp-macros/src/tool_handler.rs
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Expand Up @@ -7,6 +7,7 @@ use syn::{Expr, ImplItem, ItemImpl};
#[darling(default)]
pub struct ToolHandlerAttribute {
pub router: Expr,
pub meta: Option<Expr>,
}

impl Default for ToolHandlerAttribute {
Expand All @@ -16,13 +17,14 @@ impl Default for ToolHandlerAttribute {
self.tool_router
})
.unwrap(),
meta: None,
}
}
}

pub fn tool_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenStream> {
let attr_args = NestedMeta::parse_meta_list(attr)?;
let ToolHandlerAttribute { router } = ToolHandlerAttribute::from_list(&attr_args)?;
let ToolHandlerAttribute { router, meta } = ToolHandlerAttribute::from_list(&attr_args)?;
let mut item_impl = syn::parse2::<ItemImpl>(input.clone())?;
let tool_call_fn = quote! {
async fn call_tool(
Expand All @@ -34,13 +36,24 @@ pub fn tool_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
#router.call(tcc).await
}
};

let result_meta = if let Some(meta) = meta {
quote! { Some(#meta) }
} else {
quote! { None }
};

let tool_list_fn = quote! {
async fn list_tools(
&self,
_request: Option<rmcp::model::PaginatedRequestParam>,
_context: rmcp::service::RequestContext<rmcp::RoleServer>,
) -> Result<rmcp::model::ListToolsResult, rmcp::ErrorData> {
Ok(rmcp::model::ListToolsResult::with_all_items(#router.list_all()))
Ok(rmcp::model::ListToolsResult{
tools: #router.list_all(),
meta: #result_meta,
next_cursor: None,
})
}
};
let tool_call_fn = syn::parse2::<ImplItem>(tool_call_fn)?;
Expand Down
4 changes: 2 additions & 2 deletions crates/rmcp/src/handler/server/router.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -102,7 +102,7 @@ where
let tools = self.tool_router.list_all();
Ok(ServerResult::ListToolsResult(ListToolsResult {
tools,
next_cursor: None,
..Default::default()
}))
}
ClientRequest::GetPromptRequest(request) => {
Expand All @@ -125,7 +125,7 @@ where
let prompts = self.prompt_router.list_all();
Ok(ServerResult::ListPromptsResult(ListPromptsResult {
prompts,
next_cursor: None,
..Default::default()
}))
}
rest => self.service.handle_request(rest, context).await,
Expand Down
3 changes: 3 additions & 0 deletions crates/rmcp/src/model.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -794,6 +794,8 @@ macro_rules! paginated_result {
#[serde(rename_all = "camelCase")]
#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
pub struct $t {
#[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
pub meta: Option<Meta>,
Comment on lines +797 to +798
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Copilot AI Nov 24, 2025

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[nitpick] Field ordering inconsistency: The meta field is placed first in paginated result structs, but in entity structs like Tool, Resource, and Prompt, the meta field is placed last (after icons). For consistency, consider placing meta last in this macro as well, after next_cursor and the items field. This would match the convention used in other structs throughout the codebase.

Copilot uses AI. Check for mistakes.
#[serde(skip_serializing_if = "Option::is_none")]
pub next_cursor: Option<Cursor>,
pub $i_item: $t_item,
Expand All @@ -804,6 +806,7 @@ macro_rules! paginated_result {
items: $t_item,
) -> Self {
Self {
meta: None,
next_cursor: None,
$i_item: items,
}
Expand Down
1 change: 1 addition & 0 deletions crates/rmcp/src/model/content.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,7 @@ mod tests {
mime_type: Some("text/plain".to_string()),
size: Some(100),
icons: None,
meta: None,
});

let json = serde_json::to_string(&resource_link).unwrap();
Expand Down
6 changes: 5 additions & 1 deletion crates/rmcp/src/model/prompt.rs
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Expand Up @@ -2,7 +2,7 @@ use base64::engine::{Engine, general_purpose::STANDARD as BASE64_STANDARD};
use serde::{Deserialize, Serialize};

use super::{
AnnotateAble, Annotations, Icon, RawEmbeddedResource, RawImageContent,
AnnotateAble, Annotations, Icon, Meta, RawEmbeddedResource, RawImageContent,
content::{EmbeddedResource, ImageContent},
resource::ResourceContents,
};
Expand All @@ -25,6 +25,9 @@ pub struct Prompt {
/// Optional list of icons for the prompt
#[serde(skip_serializing_if = "Option::is_none")]
pub icons: Option<Vec<Icon>>,
/// Optional additional metadata for this prompt
#[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
pub meta: Option<Meta>,
}

impl Prompt {
Expand All @@ -44,6 +47,7 @@ impl Prompt {
description: description.map(Into::into),
arguments,
icons: None,
meta: None,
}
}
}
Expand Down
5 changes: 5 additions & 0 deletions crates/rmcp/src/model/resource.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,9 @@ pub struct RawResource {
/// Optional list of icons for the resource
#[serde(skip_serializing_if = "Option::is_none")]
pub icons: Option<Vec<Icon>>,
/// Optional additional metadata for this resource
#[serde(rename = "_meta", skip_serializing_if = "Option::is_none")]
pub meta: Option<Meta>,
}

pub type Resource = Annotated<RawResource>;
Expand Down Expand Up @@ -95,6 +98,7 @@ impl RawResource {
mime_type: None,
size: None,
icons: None,
meta: None,
}
}
}
Expand All @@ -115,6 +119,7 @@ mod tests {
mime_type: Some("text/plain".to_string()),
size: Some(100),
icons: None,
meta: None,
};

let json = serde_json::to_string(&resource).unwrap();
Expand Down
8 changes: 8 additions & 0 deletions crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -976,6 +976,14 @@
"description": "Represents a resource in the extension with metadata",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this resource",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"description": {
"description": "Optional description of the resource",
"type": [
Expand Down
8 changes: 8 additions & 0 deletions crates/rmcp/tests/test_message_schema/client_json_rpc_message_schema_current.json
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Original file line number Diff line number Diff line change
Expand Up @@ -976,6 +976,14 @@
"description": "Represents a resource in the extension with metadata",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this resource",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"description": {
"description": "Optional description of the resource",
"type": [
Expand Down
60 changes: 60 additions & 0 deletions crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,14 @@
"description": "Represents a resource in the extension with metadata",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this resource",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"annotations": {
"anyOf": [
{
Expand Down Expand Up @@ -1031,6 +1039,13 @@
"ListPromptsResult": {
"type": "object",
"properties": {
"_meta": {
"type": [
"object",
"null"
],
"additionalProperties": true
},
"nextCursor": {
"type": [
"string",
Expand All @@ -1051,6 +1066,13 @@
"ListResourceTemplatesResult": {
"type": "object",
"properties": {
"_meta": {
"type": [
"object",
"null"
],
"additionalProperties": true
},
"nextCursor": {
"type": [
"string",
Expand All @@ -1071,6 +1093,13 @@
"ListResourcesResult": {
"type": "object",
"properties": {
"_meta": {
"type": [
"object",
"null"
],
"additionalProperties": true
},
"nextCursor": {
"type": [
"string",
Expand All @@ -1096,6 +1125,13 @@
"ListToolsResult": {
"type": "object",
"properties": {
"_meta": {
"type": [
"object",
"null"
],
"additionalProperties": true
},
"nextCursor": {
"type": [
"string",
Expand Down Expand Up @@ -1472,6 +1508,14 @@
"description": "A prompt that can be used to generate text from a model",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this prompt",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"arguments": {
"description": "Optional arguments that can be passed to customize the prompt",
"type": [
Expand Down Expand Up @@ -1660,6 +1704,14 @@
"description": "A link to a resource that can be fetched separately",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this resource",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"annotations": {
"anyOf": [
{
Expand Down Expand Up @@ -1816,6 +1868,14 @@
"description": "Represents a resource in the extension with metadata",
"type": "object",
"properties": {
"_meta": {
"description": "Optional additional metadata for this resource",
"type": [
"object",
"null"
],
"additionalProperties": true
},
"description": {
"description": "Optional description of the resource",
"type": [
Expand Down
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