{"record":{"id":"fe50f7b3161e08a9","repo":"abpframework/abp","slug":"failed-to-fetch-tool-definitions-errormessage","errorCode":null,"errorMessage":"Failed to fetch tool definitions: {errorMessage}","messagePattern":"Failed to fetch tool definitions: (.+?)","errorType":"exception","errorClass":"CliUsageException","httpStatus":null,"severity":"error","filePath":"framework/src/Volo.Abp.Cli.Core/Volo/Abp/Cli/Commands/Services/McpHttpClientService.cs","lineNumber":149,"sourceCode":"    public async Task<List<McpToolDefinition>> GetToolDefinitionsAsync()\n    {\n        _mcpLogger.Debug(LogSource, $\"GetToolDefinitionsAsync called. Instance={GetHashCode()}\");\n        \n        var baseUrl = await GetMcpServerUrlAsync();\n        var url = $\"{baseUrl}/tools\";\n\n        try\n        {\n            using var httpClient = _httpClientFactory.CreateClient(needsAuthentication: true);\n            var response = await httpClient.GetAsync(url);\n\n            if (!response.IsSuccessStatusCode)\n            {\n                _mcpLogger.Error(LogSource, $\"Failed to fetch tool definitions with status: {response.StatusCode}\");\n                \n                // Throw sanitized exception\n                var errorMessage = GetSanitizedHttpErrorMessage(response.StatusCode);\n                throw new CliUsageException($\"Failed to fetch tool definitions: {errorMessage}\");\n            }\n\n            var responseContent = await response.Content.ReadAsStringAsync();\n            \n            // The API returns { tools: [...] } format\n            var result = JsonSerializer.Deserialize<McpToolsResponse>(responseContent, JsonSerializerOptionsWeb);\n            var tools = result?.Tools ?? new List<McpToolDefinition>();\n            \n            // Cache tool names for validation\n            _validToolNames = tools.Select(t => t.Name).ToList();\n            _toolDefinitionsLoaded = true;\n            \n            _mcpLogger.Debug(LogSource, $\"Tool definitions loaded successfully. _toolDefinitionsLoaded={_toolDefinitionsLoaded}, Tool count={tools.Count}, Instance={GetHashCode()}\");\n            \n            return tools;\n        }\n        catch (HttpRequestException ex)\n        {","sourceCodeStart":131,"sourceCodeEnd":167,"githubUrl":"https://github.com/abpframework/abp/blob/7ed43b1931b9df46a50c0c59148a18645641d0df/framework/src/Volo.Abp.Cli.Core/Volo/Abp/Cli/Commands/Services/McpHttpClientService.cs#L131-L167","documentation":"Thrown by McpHttpClientService.GetToolDefinitionsAsync when the HTTP GET request to {baseUrl}/tools returns a non-success HTTP status code. The error message is sanitized via GetSanitizedHttpErrorMessage to avoid exposing raw server responses. Status code mappings include: 401 -> authentication failure, 403 -> access denied, 404 -> tool not found, 429 -> rate limit, 503 -> service unavailable.","triggerScenarios":"The ABP.IO MCP server's /tools endpoint returns an error HTTP status. This occurs when: the CLI is not authenticated (401), the account lacks MCP feature access (403), the server is rate-limiting (429), or the server is down (503/500). The HTTP client is created with needsAuthentication: true, so it includes auth headers.","commonSituations":"CLI not logged in (run 'abp login'), expired authentication token, ABP Commercial license expired or insufficient tier for MCP features, ABP.IO server outage or maintenance, corporate proxy blocking access, rate limiting from too many requests.","solutions":["Run 'abp login' to authenticate with your ABP account","Verify your ABP Commercial license is active and covers MCP tool access","Wait 30-60 seconds and retry if rate-limited (429 status)","Check ABP.IO service status pages for known outages","Verify network/proxy/firewall allows outbound HTTPS to the MCP server URL","If using a custom MCP server URL, verify it in CliPaths.McpConfig"],"exampleFix":null,"handlingStrategy":"retry","validationCode":"// Pre-check: verify authentication and server reachability before fetching tools\nvar isHealthy = await _mcpHttpClient.CheckServerHealthAsync();\nif (!isHealthy)\n{\n    Console.Error.WriteLine(\"MCP server is not reachable. Check network and authentication.\");\n    return;\n}","typeGuard":null,"tryCatchPattern":"// Retry with exponential backoff for transient HTTP failures\nasync Task<List<McpToolDefinition>> FetchWithRetry(int maxRetries = 3)\n{\n    for (int i = 0; i < maxRetries; i++)\n    {\n        try\n        {\n            return await _mcpHttpClient.GetToolDefinitionsAsync();\n        }\n        catch (CliUsageException ex) when (ex.Message.Contains(\"Failed to fetch\") && i < maxRetries - 1)\n        {\n            await Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, i)));\n        }\n    }\n    throw new InvalidOperationException(\"Failed to fetch tool definitions after retries.\");\n}","preventionTips":["Run 'abp login' before starting the MCP server to ensure valid auth tokens","Keep your ABP Commercial license active and verify it covers MCP features","Implement retry logic for transient HTTP errors (429, 503)","Monitor ABP.IO service status for planned maintenance windows"],"tags":["mcp","network","authentication","tool-definitions","http-error"],"backgroundTag":null,"analyzedSha":"7ed43b1931b9df46a50c0c59148a18645641d0df","analyzedAt":"2026-08-13T16:26:11.351Z","schemaVersion":2},"datasetVersion":"2026-08-13T19:17:28.613Z"}