feat: mcp sdk conformance (#687)

* adds conformance server and client
* adds results from initial run of https://github.com/modelcontextprotocol/conformance/tree/main/.claude/skills/mcp-sdk-tier-audit skill
* various small changes applied during the testing loop

Co-authored-by: Dale Seo <5466341+DaleSeo@users.noreply.github.com>
This commit is contained in:
Alex Hancock 2026-02-26 13:33:18 -05:00 • committed by GitHub
commit a7e4ae3203
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@ -0,0 +1,959 @@
use std::{collections::HashSet, future::Future, sync::Arc};
use rmcp::{
ErrorData, RoleServer, ServerHandler,
model::*,
service::RequestContext,
transport::{
StreamableHttpServerConfig, StreamableHttpService,
streamable_http_server::session::local::LocalSessionManager,
},
};
use serde_json::{Value, json};
use tokio::sync::Mutex;
use tracing_subscriber::EnvFilter;
// Small base64-encoded 1x1 red PNG
const TEST_IMAGE_DATA: &str = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8/5+hHgAHggJ/PchI7wAAAABJRU5ErkJggg==";
// Small base64-encoded WAV (silence)
const TEST_AUDIO_DATA: &str = "UklGRiQAAABXQVZFZm10IBAAAAABAAEARKwAAIhYAQACABAAZGF0YQAAAAA=";
/// Helper to convert a serde_json::Value (must be an object) into a JsonObject
fn json_object(v: Value) -> JsonObject {
match v {
Value::Object(map) => map,
_ => panic!("Expected JSON object"),
}
}
#[derive(Clone)]
struct ConformanceServer {
subscriptions: Arc<Mutex<HashSet<String>>>,
log_level: Arc<Mutex<LoggingLevel>>,
}
impl ConformanceServer {
fn new() -> Self {
Self {
subscriptions: Arc::new(Mutex::new(HashSet::new())),
log_level: Arc::new(Mutex::new(LoggingLevel::Debug)),
}
}
}
impl ServerHandler for ConformanceServer {
fn initialize(
&self,
_request: InitializeRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<InitializeResult, ErrorData>> + Send + '_ {
async {
Ok(InitializeResult {
server_info: Implementation {
name: "rust-conformance-server".into(),
title: None,
version: "0.1.0".into(),
description: None,
icons: None,
website_url: None,
},
capabilities: ServerCapabilities::builder()
.enable_prompts()
.enable_resources()
.enable_tools()
.enable_logging()
.build(),
instructions: Some("Rust MCP conformance test server".into()),
..Default::default()
})
}
}
fn ping(
&self,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<(), ErrorData>> + Send + '_ {
async { Ok(()) }
}
fn list_tools(
&self,
_request: Option<PaginatedRequestParams>,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<ListToolsResult, ErrorData>> + Send + '_ {
async {
let tools = vec![
Tool::new(
"test_simple_text",
"Returns simple text content",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_image_content",
"Returns image content",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_audio_content",
"Returns audio content",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_embedded_resource",
"Returns embedded resource content",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_multiple_content_types",
"Returns multiple content types",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_tool_with_logging",
"Sends logging notifications during execution",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_error_handling",
"Always returns an error",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_tool_with_progress",
"Reports progress notifications",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_sampling",
"Requests LLM sampling from client",
json_object(json!({
"type": "object",
"properties": {
"prompt": { "type": "string", "description": "The prompt to send" }
},
"required": ["prompt"]
})),
),
Tool::new(
"test_elicitation",
"Requests user input from client",
json_object(json!({
"type": "object",
"properties": {
"message": { "type": "string", "description": "The message to show" }
},
"required": ["message"]
})),
),
Tool::new(
"test_elicitation_sep1034_defaults",
"Tests elicitation with default values (SEP-1034)",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"test_elicitation_sep1330_enums",
"Tests enum schema improvements (SEP-1330)",
json_object(json!({
"type": "object",
"properties": {}
})),
),
Tool::new(
"json_schema_2020_12_tool",
"Tool with JSON Schema 2020-12 features",
json_object(json!({
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"$defs": {
"address": {
"type": "object",
"properties": {
"street": { "type": "string" },
"city": { "type": "string" }
}
}
},
"properties": {
"name": { "type": "string" },
"address": { "$ref": "#/$defs/address" }
},
"additionalProperties": false
})),
),
Tool::new(
"test_reconnection",
"Tests SSE reconnection behavior",
json_object(json!({
"type": "object",
"properties": {}
})),
),
];
Ok(ListToolsResult {
meta: None,
tools,
next_cursor: None,
})
}
}
fn call_tool(
&self,
request: CallToolRequestParams,
cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<CallToolResult, ErrorData>> + Send + '_ {
async move {
let args = request.arguments.unwrap_or_default();
match request.name.as_ref() {
"test_simple_text" => Ok(CallToolResult {
content: vec![Content::text("This is a simple text response for testing.")],
structured_content: None,
is_error: None,
meta: None,
}),
"test_image_content" => Ok(CallToolResult {
content: vec![Content::image(TEST_IMAGE_DATA, "image/png")],
structured_content: None,
is_error: None,
meta: None,
}),
"test_audio_content" => {
// No Content::audio() helper, construct manually
let audio = RawContent::Audio(RawAudioContent {
data: TEST_AUDIO_DATA.into(),
mime_type: "audio/wav".into(),
})
.no_annotation();
Ok(CallToolResult {
content: vec![audio],
structured_content: None,
is_error: None,
meta: None,
})
}
"test_embedded_resource" => Ok(CallToolResult {
content: vec![Content::resource(ResourceContents::TextResourceContents {
uri: "test://embedded-resource".into(),
mime_type: Some("text/plain".into()),
text: "This is an embedded resource content.".into(),
meta: None,
})],
structured_content: None,
is_error: None,
meta: None,
}),
"test_multiple_content_types" => Ok(CallToolResult {
content: vec![
Content::text("Multiple content types test:"),
Content::image(TEST_IMAGE_DATA, "image/png"),
Content::resource(ResourceContents::TextResourceContents {
uri: "test://mixed-content-resource".into(),
mime_type: Some("application/json".into()),
text: r#"{"test":"data","value":123}"#.into(),
meta: None,
}),
],
structured_content: None,
is_error: None,
meta: None,
}),
"test_tool_with_logging" => {
for msg in [
"Tool execution started",
"Tool processing data",
"Tool execution completed",
] {
let _ = cx
.peer
.notify_logging_message(LoggingMessageNotificationParam {
level: LoggingLevel::Info,
logger: Some("conformance-server".into()),
data: json!(msg),
})
.await;
tokio::time::sleep(tokio::time::Duration::from_millis(50)).await;
}
Ok(CallToolResult {
content: vec![Content::text("Logging test completed")],
structured_content: None,
is_error: None,
meta: None,
})
}
"test_error_handling" => Ok(CallToolResult {
content: vec![Content::text(
"This tool intentionally returns an error for testing",
)],
structured_content: None,
is_error: Some(true),
meta: None,
}),
"test_tool_with_progress" => {
let progress_token = cx.meta.get_progress_token();
for (progress, message) in
[(0.0, "Starting"), (50.0, "Halfway"), (100.0, "Complete")]
{
if let Some(token) = &progress_token {
let _ = cx
.peer
.notify_progress(ProgressNotificationParam {
progress_token: token.clone(),
progress,
total: Some(100.0),
message: Some(message.into()),
})
.await;
}
tokio::time::sleep(tokio::time::Duration::from_millis(50)).await;
}
Ok(CallToolResult {
content: vec![Content::text("Progress test completed")],
structured_content: None,
is_error: None,
meta: None,
})
}
"test_sampling" => {
let prompt = args
.get("prompt")
.and_then(|v| v.as_str())
.unwrap_or("Hello");
match cx
.peer
.create_message(CreateMessageRequestParams {
meta: None,
task: None,
messages: vec![SamplingMessage::user_text(prompt)],
max_tokens: 100,
model_preferences: None,
system_prompt: None,
include_context: None,
temperature: None,
stop_sequences: None,
metadata: None,
tools: None,
tool_choice: None,
})
.await
{
Ok(result) => {
let text = result
.message
.content
.first()
.and_then(|c| c.as_text())
.map(|t| t.text.clone())
.unwrap_or_else(|| "No text response".into());
Ok(CallToolResult {
content: vec![Content::text(format!("LLM response: {}", text))],
structured_content: None,
is_error: None,
meta: None,
})
}
Err(e) => Ok(CallToolResult {
content: vec![Content::text(format!("Sampling error: {}", e))],
structured_content: None,
is_error: Some(true),
meta: None,
}),
}
}
"test_elicitation" => {
let message = args
.get("message")
.and_then(|v| v.as_str())
.unwrap_or("Please provide your information");
let schema_json = json!({
"type": "object",
"properties": {
"username": {
"type": "string",
"description": "User's response"
},
"email": {
"type": "string",
"description": "User's email address"
}
},
"required": ["username", "email"]
});
let schema: ElicitationSchema = serde_json::from_value(schema_json).unwrap();
match cx
.peer
.create_elicitation(CreateElicitationRequestParams::FormElicitationParams {
meta: None,
message: message.into(),
requested_schema: schema,
})
.await
{
Ok(result) => Ok(CallToolResult {
content: vec![Content::text(format!(
"User response: action={}, content={:?}",
match result.action {
ElicitationAction::Accept => "accept",
ElicitationAction::Decline => "decline",
ElicitationAction::Cancel => "cancel",
},
result.content
))],
structured_content: None,
is_error: None,
meta: None,
}),
Err(e) => Ok(CallToolResult {
content: vec![Content::text(format!("Elicitation error: {}", e))],
structured_content: None,
is_error: Some(true),
meta: None,
}),
}
}
"test_elicitation_sep1034_defaults" => {
let schema_json = json!({
"type": "object",
"properties": {
"name": {
"type": "string",
"description": "User's name",
"default": "John Doe"
},
"age": {
"type": "integer",
"description": "User's age",
"default": 30
},
"score": {
"type": "number",
"description": "User's score",
"default": 95.5
},
"status": {
"type": "string",
"description": "User's status",
"enum": ["active", "inactive", "pending"],
"default": "active"
},
"verified": {
"type": "boolean",
"description": "Whether user is verified",
"default": true
}
}
});
let schema: ElicitationSchema = serde_json::from_value(schema_json).unwrap();
match cx
.peer
.create_elicitation(CreateElicitationRequestParams::FormElicitationParams {
meta: None,
message: "Please provide values (all have defaults)".into(),
requested_schema: schema,
})
.await
{
Ok(result) => Ok(CallToolResult {
content: vec![Content::text(format!(
"Elicitation completed: action={}, content={:?}",
match result.action {
ElicitationAction::Accept => "accept",
ElicitationAction::Decline => "decline",
ElicitationAction::Cancel => "cancel",
},
result.content
))],
structured_content: None,
is_error: None,
meta: None,
}),
Err(e) => Ok(CallToolResult {
content: vec![Content::text(format!("Elicitation error: {}", e))],
structured_content: None,
is_error: Some(true),
meta: None,
}),
}
}
"test_elicitation_sep1330_enums" => {
let schema_json = json!({
"type": "object",
"properties": {
"untitledSingle": {
"type": "string",
"enum": ["option1", "option2", "option3"]
},
"titledSingle": {
"type": "string",
"oneOf": [
{ "const": "value1", "title": "First Option" },
{ "const": "value2", "title": "Second Option" },
{ "const": "value3", "title": "Third Option" }
]
},
"legacyEnum": {
"type": "string",
"enum": ["opt1", "opt2", "opt3"],
"enumNames": ["Option One", "Option Two", "Option Three"]
},
"untitledMulti": {
"type": "array",
"items": {
"type": "string",
"enum": ["option1", "option2", "option3"]
}
},
"titledMulti": {
"type": "array",
"items": {
"anyOf": [
{ "const": "value1", "title": "First Choice" },
{ "const": "value2", "title": "Second Choice" },
{ "const": "value3", "title": "Third Choice" }
]
}
}
}
});
let schema: ElicitationSchema = serde_json::from_value(schema_json).unwrap();
match cx
.peer
.create_elicitation(CreateElicitationRequestParams::FormElicitationParams {
meta: None,
message: "Test enum schema improvements".into(),
requested_schema: schema,
})
.await
{
Ok(result) => Ok(CallToolResult {
content: vec![Content::text(format!(
"Enum elicitation completed: action={}",
match result.action {
ElicitationAction::Accept => "accept",
ElicitationAction::Decline => "decline",
ElicitationAction::Cancel => "cancel",
}
))],
structured_content: None,
is_error: None,
meta: None,
}),
Err(e) => Ok(CallToolResult {
content: vec![Content::text(format!("Elicitation error: {}", e))],
structured_content: None,
is_error: Some(true),
meta: None,
}),
}
}
"json_schema_2020_12_tool" => {
let name = args.get("name").and_then(|v| v.as_str()).unwrap_or("world");
Ok(CallToolResult {
content: vec![Content::text(format!("Hello, {}!", name))],
structured_content: None,
is_error: None,
meta: None,
})
}
"test_reconnection" => {
tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
Ok(CallToolResult {
content: vec![Content::text("Reconnection test completed")],
structured_content: None,
is_error: None,
meta: None,
})
}
_ => Err(ErrorData::invalid_params(
format!("Unknown tool: {}", request.name),
None,
)),
}
}
}
fn list_resources(
&self,
_request: Option<PaginatedRequestParams>,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<ListResourcesResult, ErrorData>> + Send + '_ {
async {
Ok(ListResourcesResult {
meta: None,
resources: vec![
RawResource {
uri: "test://static-text".into(),
name: "Static Text Resource".into(),
title: None,
description: Some("A static text resource for testing".into()),
mime_type: Some("text/plain".into()),
size: None,
icons: None,
meta: None,
}
.no_annotation(),
RawResource {
uri: "test://static-binary".into(),
name: "Static Binary Resource".into(),
title: None,
description: Some("A static binary/blob resource for testing".into()),
mime_type: Some("image/png".into()),
size: None,
icons: None,
meta: None,
}
.no_annotation(),
],
next_cursor: None,
})
}
}
fn read_resource(
&self,
request: ReadResourceRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<ReadResourceResult, ErrorData>> + Send + '_ {
async move {
let uri = request.uri.as_str();
match uri {
"test://static-text" => Ok(ReadResourceResult {
contents: vec![ResourceContents::TextResourceContents {
uri: uri.into(),
mime_type: Some("text/plain".into()),
text: "This is the content of the static text resource.".into(),
meta: None,
}],
}),
"test://static-binary" => Ok(ReadResourceResult {
contents: vec![ResourceContents::BlobResourceContents {
uri: uri.into(),
mime_type: Some("image/png".into()),
blob: TEST_IMAGE_DATA.into(),
meta: None,
}],
}),
_ => {
// Check if it matches template: test://template/{id}/data
if uri.starts_with("test://template/") && uri.ends_with("/data") {
let id = uri
.strip_prefix("test://template/")
.and_then(|s| s.strip_suffix("/data"))
.unwrap_or("unknown");
Ok(ReadResourceResult {
contents: vec![ResourceContents::TextResourceContents {
uri: uri.into(),
mime_type: Some("application/json".into()),
text: format!(
r#"{{"id":"{}","templateTest":true,"data":"Data for ID: {}"}}"#,
id, id
),
meta: None,
}],
})
} else {
Err(ErrorData::resource_not_found(
format!("Resource not found: {}", uri),
None,
))
}
}
}
}
}
fn list_resource_templates(
&self,
_request: Option<PaginatedRequestParams>,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<ListResourceTemplatesResult, ErrorData>> + Send + '_ {
async {
Ok(ListResourceTemplatesResult {
meta: None,
resource_templates: vec![
RawResourceTemplate {
uri_template: "test://template/{id}/data".into(),
name: "Dynamic Resource".into(),
title: None,
description: Some("A dynamic resource with parameter substitution".into()),
mime_type: Some("application/json".into()),
icons: None,
}
.no_annotation(),
],
next_cursor: None,
})
}
}
fn subscribe(
&self,
request: SubscribeRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<(), ErrorData>> + Send + '_ {
async move {
let mut subs = self.subscriptions.lock().await;
subs.insert(request.uri.to_string());
Ok(())
}
}
fn unsubscribe(
&self,
request: UnsubscribeRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<(), ErrorData>> + Send + '_ {
async move {
let mut subs = self.subscriptions.lock().await;
subs.remove(request.uri.as_str());
Ok(())
}
}
fn list_prompts(
&self,
_request: Option<PaginatedRequestParams>,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<ListPromptsResult, ErrorData>> + Send + '_ {
async {
Ok(ListPromptsResult {
meta: None,
prompts: vec![
Prompt::new(
"test_simple_prompt",
Some("A simple test prompt with no arguments"),
None,
),
Prompt::new(
"test_prompt_with_arguments",
Some("A test prompt that accepts arguments"),
Some(vec![
PromptArgument {
name: "name".into(),
title: None,
description: Some("The name to greet".into()),
required: Some(true),
},
PromptArgument {
name: "style".into(),
title: None,
description: Some("The greeting style".into()),
required: Some(false),
},
]),
),
Prompt::new(
"test_prompt_with_embedded_resource",
Some("A test prompt that includes an embedded resource"),
None,
),
Prompt::new(
"test_prompt_with_image",
Some("A test prompt that includes an image"),
None,
),
],
next_cursor: None,
})
}
}
fn get_prompt(
&self,
request: GetPromptRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<GetPromptResult, ErrorData>> + Send + '_ {
async move {
match request.name.as_str() {
"test_simple_prompt" => Ok(GetPromptResult {
description: Some("A simple test prompt".into()),
messages: vec![PromptMessage::new_text(
PromptMessageRole::User,
"This is a simple test prompt.",
)],
}),
"test_prompt_with_arguments" => {
let args = request.arguments.unwrap_or_default();
let name = args.get("name").and_then(|v| v.as_str()).unwrap_or("World");
let style = args
.get("style")
.and_then(|v| v.as_str())
.unwrap_or("friendly");
Ok(GetPromptResult {
description: Some("A prompt with arguments".into()),
messages: vec![PromptMessage::new_text(
PromptMessageRole::User,
format!("Please greet {} in a {} style.", name, style),
)],
})
}
"test_prompt_with_embedded_resource" => Ok(GetPromptResult {
description: Some("A prompt with an embedded resource".into()),
messages: vec![
PromptMessage::new_text(PromptMessageRole::User, "Here is a resource:"),
PromptMessage::new_resource(
PromptMessageRole::User,
"test://static-text".into(),
Some("text/plain".into()),
Some("Resource content for prompt".into()),
None,
None,
None,
),
],
}),
"test_prompt_with_image" => {
let image_content = RawImageContent {
data: TEST_IMAGE_DATA.into(),
mime_type: "image/png".into(),
meta: None,
};
Ok(GetPromptResult {
description: Some("A prompt with an image".into()),
messages: vec![
PromptMessage::new_text(PromptMessageRole::User, "Here is an image:"),
PromptMessage {
role: PromptMessageRole::User,
content: PromptMessageContent::Image {
image: image_content.no_annotation(),
},
},
],
})
}
_ => Err(ErrorData::invalid_params(
format!("Unknown prompt: {}", request.name),
None,
)),
}
}
}
fn complete(
&self,
request: CompleteRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<CompleteResult, ErrorData>> + Send + '_ {
async move {
let values = match &request.r#ref {
Reference::Resource(_) => {
if request.argument.name == "id" {
vec!["1".into(), "2".into(), "3".into()]
} else {
vec![]
}
}
Reference::Prompt(prompt_ref) => {
if request.argument.name == "name" {
vec!["Alice".into(), "Bob".into(), "Charlie".into()]
} else if request.argument.name == "style" {
vec!["friendly".into(), "formal".into(), "casual".into()]
} else {
vec![prompt_ref.name.clone()]
}
}
};
Ok(CompleteResult {
completion: CompletionInfo::new(values)
.map_err(|e| ErrorData::internal_error(e, None))?,
})
}
}
fn set_level(
&self,
request: SetLevelRequestParams,
_cx: RequestContext<RoleServer>,
) -> impl Future<Output = Result<(), ErrorData>> + Send + '_ {
async move {
let mut level = self.log_level.lock().await;
*level = request.level;
Ok(())
}
}
}
#[tokio::main]
async fn main() -> anyhow::Result<()> {
tracing_subscriber::fmt()
.with_env_filter(EnvFilter::from_default_env().add_directive(tracing::Level::INFO.into()))
.init();
let port: u16 = std::env::var("PORT")
.ok()
.and_then(|p| p.parse().ok())
.unwrap_or(8001);
let bind_addr = format!("127.0.0.1:{}", port);
tracing::info!("Starting conformance server on {}", bind_addr);
let server = ConformanceServer::new();
let config = StreamableHttpServerConfig {
stateful_mode: true,
..Default::default()
};
let service = StreamableHttpService::new(
move || Ok(server.clone()),
LocalSessionManager::default().into(),
config,
);
let router = axum::Router::new().nest_service("/mcp", service);
let listener = tokio::net::TcpListener::bind(&bind_addr).await?;
tracing::info!("Conformance server listening on http://{}/mcp", bind_addr);
axum::serve(listener, router).await?;
Ok(())
}