forked from xiaozhi/xiaozhi-esp32
Add MCP server
This commit is contained in:
Terrence
269
main/mcp_server.cc
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269
main/mcp_server.cc
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/*
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* MCP Server Implementation
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* Reference: https://modelcontextprotocol.io/specification/2024-11-05
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*/
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#include "mcp_server.h"
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#include <esp_log.h>
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#include <esp_app_desc.h>
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#include <algorithm>
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#include <cstring>
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#include "application.h"
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#include "display.h"
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#include "board.h"
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#define TAG "MCP"
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McpServer::McpServer() {
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AddCommonTools();
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}
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void McpServer::AddCommonTools() {
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AddTool("self.get_device_status",
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"Provides the real-time information of the device, including the current status of the audio speaker, screen, battery, network, etc.\n"
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"Use this tool for: \n"
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"1. Answering questions about current condition (e.g. what is the current volume of the audio speaker?)\n"
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"2. As the first step to control the device (e.g. turn up / down the volume of the audio speaker, etc.)",
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PropertyList(),
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[](const PropertyList& properties) -> ReturnValue {
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return Board::GetInstance().GetDeviceStatusJson();
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});
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AddTool("self.speaker.set_volume",
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"Set the volume of the audio speaker. If the current volume is unknown, you must call `self.get_device_status` tool first and then call this tool.",
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PropertyList({
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Property("volume", kPropertyTypeInteger, 0, 100)
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}),
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[](const PropertyList& properties) -> ReturnValue {
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auto codec = Board::GetInstance().GetAudioCodec();
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codec->SetOutputVolume(properties["volume"].value<int>());
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return true;
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});
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AddTool("self.screen.set_brightness",
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"Set the brightness of the screen.",
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PropertyList({
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Property("brightness", kPropertyTypeInteger, 0, 100)
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}),
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[](const PropertyList& properties) -> ReturnValue {
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uint8_t brightness = static_cast<uint8_t>(properties["brightness"].value<int>());
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auto backlight = Board::GetInstance().GetBacklight();
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if (backlight) {
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backlight->SetBrightness(brightness, true);
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}
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return true;
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});
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AddTool("self.screen.set_theme",
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"Set the theme of the screen. The theme can be 'light' or 'dark'.",
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PropertyList({
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Property("theme", kPropertyTypeString)
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}),
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[](const PropertyList& properties) -> ReturnValue {
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auto display = Board::GetInstance().GetDisplay();
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if (display) {
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display->SetTheme(properties["theme"].value<std::string>().c_str());
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}
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return true;
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});
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}
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void McpServer::AddTool(McpTool* tool) {
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tools_.push_back(tool);
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}
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void McpServer::AddTool(const std::string& name, const std::string& description, const PropertyList& properties, std::function<ReturnValue(const PropertyList&)> callback) {
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tools_.push_back(new McpTool(name, description, properties, callback));
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}
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void McpServer::ParseMessage(const std::string& message) {
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cJSON* json = cJSON_Parse(message.c_str());
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if (json == nullptr) {
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ESP_LOGE(TAG, "Failed to parse MCP message: %s", message.c_str());
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return;
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}
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ParseMessage(json);
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cJSON_Delete(json);
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}
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void McpServer::ParseMessage(const cJSON* json) {
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// Check JSONRPC version
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auto version = cJSON_GetObjectItem(json, "jsonrpc");
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if (version == nullptr || !cJSON_IsString(version) || strcmp(version->valuestring, "2.0") != 0) {
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ESP_LOGE(TAG, "Invalid JSONRPC version: %s", version ? version->valuestring : "null");
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return;
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}
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// Check method
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auto method = cJSON_GetObjectItem(json, "method");
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if (method == nullptr || !cJSON_IsString(method)) {
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ESP_LOGE(TAG, "Missing method");
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return;
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}
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auto method_str = std::string(method->valuestring);
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if (method_str.find("notifications") == 0) {
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return;
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}
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// Check params
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auto params = cJSON_GetObjectItem(json, "params");
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if (params != nullptr && !cJSON_IsObject(params)) {
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ESP_LOGE(TAG, "Invalid params for method: %s", method_str.c_str());
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return;
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}
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auto id = cJSON_GetObjectItem(json, "id");
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if (id == nullptr || !cJSON_IsNumber(id)) {
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ESP_LOGE(TAG, "Invalid id for method: %s", method_str.c_str());
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return;
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}
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auto id_int = id->valueint;
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if (method_str == "initialize") {
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auto app_desc = esp_app_get_description();
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ReplyResult(id_int, "{\"protocolVersion\":\"2024-11-05\",\"capabilities\":{\"tools\":{}},"
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"\"serverInfo\":{\"name\":\"" BOARD_NAME "\",\"version\":\"" + std::string(app_desc->version) + "\"}}");
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} else if (method_str == "tools/list") {
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std::string cursor_str = "";
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if (params != nullptr) {
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auto cursor = cJSON_GetObjectItem(params, "cursor");
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if (cJSON_IsString(cursor)) {
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cursor_str = std::string(cursor->valuestring);
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}
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}
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GetToolsList(id_int, cursor_str);
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} else if (method_str == "tools/call") {
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if (!cJSON_IsObject(params)) {
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ESP_LOGE(TAG, "tools/call: Missing params");
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ReplyError(id_int, "Missing params");
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return;
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}
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auto tool_name = cJSON_GetObjectItem(params, "name");
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if (!cJSON_IsString(tool_name)) {
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ESP_LOGE(TAG, "tools/call: Missing name");
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ReplyError(id_int, "Missing name");
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return;
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}
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auto tool_arguments = cJSON_GetObjectItem(params, "arguments");
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if (tool_arguments != nullptr && !cJSON_IsObject(tool_arguments)) {
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ESP_LOGE(TAG, "tools/call: Invalid arguments");
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ReplyError(id_int, "Invalid arguments");
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return;
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}
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DoToolCall(id_int, std::string(tool_name->valuestring), tool_arguments);
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} else {
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ESP_LOGE(TAG, "Method not implemented: %s", method_str.c_str());
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ReplyError(id_int, "Method not implemented: " + method_str);
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}
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}
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void McpServer::ReplyResult(int id, const std::string& result) {
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std::string payload = "{\"jsonrpc\":\"2.0\",\"id\":" + std::to_string(id) + ",\"result\":" + result + "}";
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Application::GetInstance().SendMcpMessage(payload);
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}
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void McpServer::ReplyError(int id, const std::string& message) {
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std::string payload = "{\"jsonrpc\":\"2.0\",\"id\":";
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payload += std::to_string(id) + ",\"error\":{\"message\":\"" + message + "\"}}";
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Application::GetInstance().SendMcpMessage(payload);
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}
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void McpServer::GetToolsList(int id, const std::string& cursor) {
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const int max_payload_size = 1400; // ML307 MQTT publish size limit
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std::string json = "{\"tools\":[";
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bool found_cursor = cursor.empty();
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auto it = tools_.begin();
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std::string next_cursor = "";
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while (it != tools_.end()) {
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// 如果我们还没有找到起始位置，继续搜索
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if (!found_cursor) {
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if ((*it)->name() == cursor) {
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found_cursor = true;
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} else {
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++it;
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continue;
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}
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}
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// 添加tool前检查大小
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std::string tool_json = (*it)->to_json() + ",";
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if (json.length() + tool_json.length() + 30 > max_payload_size) {
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// 如果添加这个tool会超出大小限制，设置next_cursor并退出循环
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next_cursor = (*it)->name();
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break;
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}
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json += tool_json;
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++it;
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}
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if (json.back() == ',') {
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json.pop_back();
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}
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if (json.back() == '[' && !tools_.empty()) {
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// 如果没有添加任何tool，返回错误
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ESP_LOGE(TAG, "tools/list: Failed to add tool %s because of payload size limit", next_cursor.c_str());
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ReplyError(id, "Failed to add tool " + next_cursor + " because of payload size limit");
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return;
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}
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if (next_cursor.empty()) {
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json += "]}";
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} else {
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json += "],\"nextCursor\":\"" + next_cursor + "\"}";
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}
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ReplyResult(id, json);
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}
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void McpServer::DoToolCall(int id, const std::string& tool_name, const cJSON* tool_arguments) {
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auto tool_iter = std::find_if(tools_.begin(), tools_.end(),
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[&tool_name](const McpTool* tool) {
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return tool->name() == tool_name;
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});
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if (tool_iter == tools_.end()) {
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ESP_LOGE(TAG, "tools/call: Unknown tool: %s", tool_name.c_str());
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ReplyError(id, "Unknown tool: " + tool_name);
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return;
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}
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PropertyList arguments = (*tool_iter)->properties();
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for (auto& argument : arguments) {
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bool found = false;
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if (cJSON_IsObject(tool_arguments)) {
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auto value = cJSON_GetObjectItem(tool_arguments, argument.name().c_str());
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if (argument.type() == kPropertyTypeBoolean && cJSON_IsBool(value)) {
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argument.set_value<bool>(value->valueint == 1);
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found = true;
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} else if (argument.type() == kPropertyTypeInteger && cJSON_IsNumber(value)) {
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argument.set_value<int>(value->valueint);
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found = true;
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} else if (argument.type() == kPropertyTypeString && cJSON_IsString(value)) {
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argument.set_value<std::string>(value->valuestring);
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found = true;
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}
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}
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if (!argument.has_default_value() && !found) {
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ESP_LOGE(TAG, "tools/call: Missing valid argument: %s", argument.name().c_str());
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ReplyError(id, "Missing valid argument: " + argument.name());
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return;
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}
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}
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Application::GetInstance().Schedule([this, id, tool_iter, arguments = std::move(arguments)]() {
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try {
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ReplyResult(id, (*tool_iter)->Call(arguments));
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} catch (const std::runtime_error& e) {
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ESP_LOGE(TAG, "tools/call: %s", e.what());
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ReplyError(id, e.what());
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}
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});
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}
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