MCP MVP

core/src/mcp/protocol.rs

@@ -0,0 +1,211 @@
+use serde::{Deserialize, Serialize};
+use serde_json::Value as JsonValue;
+
+// JSON-RPC 2.0 error codes
+pub const PARSE_ERROR: i32 = -32700;
+pub const INVALID_REQUEST: i32 = -32600;
+pub const METHOD_NOT_FOUND: i32 = -32601;
+pub const INVALID_PARAMS: i32 = -32602;
+pub const INTERNAL_ERROR: i32 = -32603;
+
+pub const PROTOCOL_VERSION: &str = "2025-03-26";
+
+// === JSON-RPC 2.0 envelope ===
+
+#[derive(Deserialize)]
+pub struct McpRequest {
+    pub jsonrpc: String,
+    pub id: Option<JsonValue>,
+    pub method: String,
+    #[serde(default)]
+    pub params: Option<JsonValue>,
+}
+
+#[derive(Serialize)]
+pub struct McpResponse {
+    pub jsonrpc: &'static str,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub id: Option<JsonValue>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub result: Option<JsonValue>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<McpError>,
+}
+
+impl McpResponse {
+    pub fn ok(id: Option<JsonValue>, result: JsonValue) -> Self {
+        Self {
+            jsonrpc: "2.0",
+            id,
+            result: Some(result),
+            error: None,
+        }
+    }
+
+    pub fn error(id: Option<JsonValue>, code: i32, message: String, data: Option<JsonValue>) -> Self {
+        Self {
+            jsonrpc: "2.0",
+            id,
+            result: None,
+            error: Some(McpError {
+                code,
+                message,
+                data,
+            }),
+        }
+    }
+}
+
+#[derive(Serialize)]
+pub struct McpError {
+    pub code: i32,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<JsonValue>,
+}
+
+// === initialize ===
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct InitializeParams {
+    pub protocol_version: String,
+    #[serde(default)]
+    pub capabilities: JsonValue,
+    #[serde(default)]
+    pub client_info: Option<ClientInfo>,
+}
+
+#[derive(Deserialize)]
+pub struct ClientInfo {
+    pub name: String,
+    #[serde(default)]
+    pub version: Option<String>,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct InitializeResult {
+    pub protocol_version: &'static str,
+    pub capabilities: ServerCapabilities,
+    pub server_info: ServerInfo,
+}
+
+#[derive(Serialize)]
+pub struct ServerCapabilities {
+    pub tools: ToolsCapability,
+    pub resources: ResourcesCapability,
+}
+
+#[derive(Serialize)]
+pub struct ToolsCapability {}
+
+#[derive(Serialize)]
+pub struct ResourcesCapability {
+    pub subscribe: bool,
+}
+
+#[derive(Serialize)]
+pub struct ServerInfo {
+    pub name: &'static str,
+    pub version: String,
+}
+
+// === tools/list ===
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ToolDefinition {
+    pub name: String,
+    pub description: String,
+    pub input_schema: JsonValue,
+}
+
+#[derive(Serialize)]
+pub struct ToolsListResult {
+    pub tools: Vec<ToolDefinition>,
+}
+
+// === tools/call ===
+
+#[derive(Deserialize)]
+pub struct ToolsCallParams {
+    pub name: String,
+    #[serde(default)]
+    pub arguments: JsonValue,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ToolsCallResult {
+    pub content: Vec<ContentBlock>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub is_error: Option<bool>,
+}
+
+#[derive(Serialize)]
+#[serde(tag = "type")]
+pub enum ContentBlock {
+    #[serde(rename = "text")]
+    Text { text: String },
+}
+
+// === resources/list ===
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ResourceDefinition {
+    pub uri: String,
+    pub name: String,
+    pub description: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub mime_type: Option<String>,
+}
+
+#[derive(Serialize)]
+pub struct ResourcesListResult {
+    pub resources: Vec<ResourceDefinition>,
+}
+
+// === resources/read ===
+
+#[derive(Deserialize)]
+pub struct ResourcesReadParams {
+    pub uri: String,
+}
+
+#[derive(Serialize)]
+pub struct ResourcesReadResult {
+    pub contents: Vec<ResourceContent>,
+}
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ResourceContent {
+    pub uri: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub mime_type: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub text: Option<String>,
+}
+
+// === resources/subscribe + unsubscribe ===
+
+#[derive(Deserialize)]
+pub struct ResourcesSubscribeParams {
+    pub uri: String,
+}
+
+#[derive(Deserialize)]
+pub struct ResourcesUnsubscribeParams {
+    pub uri: String,
+}
+
+// === Server→client notification ===
+
+#[derive(Serialize)]
+pub struct McpNotification {
+    pub jsonrpc: &'static str,
+    pub method: &'static str,
+    pub params: serde_json::Value,
+}