Add MCP probe to comprehensive health endpoint#3685
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[WIP] Add MCP checks to health endpoint
Add MCP probe to comprehensive health endpoint
Jun 26, 2026
souvikghosh04
requested review from
Alekhya-Polavarapu,
Aniruddh25,
JerryNixon,
RubenCerna2079,
aaronburtle,
anushakolan,
rusamant,
sourabh1007,
stuartpa and
vadeveka
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Pull request overview
This PR adds an MCP probe to the comprehensive /health endpoint so that MCP availability and response time are reflected in health monitoring when MCP is enabled.
Changes:
- Added a minimal JSON-RPC
initializepayload builder for MCP health probing. - Implemented
HttpUtilities.ExecuteMcpQueryAsyncand wired an MCP check intoHealthCheckHelper.UpdateHealthCheckDetailsAsync. - Extended health endpoint tests and introduced the
mcphealth-check tag constant.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| src/Service/HealthCheck/Utilities.cs | Adds helper to create a minimal MCP initialize JSON-RPC request payload. |
| src/Service/HealthCheck/HttpUtilities.cs | Adds an MCP POST probe method for the health check HTTP client. |
| src/Service/HealthCheck/HealthCheckHelper.cs | Wires MCP probing into comprehensive health checks and records duration/threshold. |
| src/Service.Tests/Configuration/HealthEndpointTests.cs | Extends comprehensive health assertions and adds MCP request unit tests. |
| src/Config/HealthCheck/HealthCheckConstants.cs | Adds the mcp tag constant. |
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| if (string.IsNullOrEmpty(mcpUriSuffix)) | ||
| { | ||
| _logger.LogError("The MCP route is not available, hence HealthEndpoint is not available."); | ||
| return errorMessage; | ||
| } | ||
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|
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| if (!Program.CheckSanityOfUrl($"{_httpClient.BaseAddress}{mcpUriSuffix.TrimStart('/')}")) | ||
| { | ||
| _logger.LogError("Blocked outbound request due to invalid or unsafe URI."); | ||
| return "Blocked outbound request due to invalid or unsafe URI."; | ||
| } | ||
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| string jsonPayload = Utilities.CreateHttpMcpQuery(); | ||
| HttpContent content = new StringContent(jsonPayload, Encoding.UTF8, Utilities.JSON_CONTENT_TYPE); | ||
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| HttpRequestMessage message = new(method: HttpMethod.Post, requestUri: mcpUriSuffix) | ||
| { | ||
| Content = content | ||
| }; |
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| private async Task<(int, string?)> ExecuteMcpQueryAsync(string mcpUriSuffix, string roleHeader, string roleToken) | ||
| { | ||
| string? errorMessage = null; | ||
| if (!string.IsNullOrEmpty(mcpUriSuffix)) | ||
| { | ||
| Stopwatch stopwatch = new(); | ||
| stopwatch.Start(); | ||
| errorMessage = await _httpUtility.ExecuteMcpQueryAsync(mcpUriSuffix, roleHeader, roleToken); | ||
| stopwatch.Stop(); | ||
| return string.IsNullOrEmpty(errorMessage) ? ((int)stopwatch.ElapsedMilliseconds, errorMessage) : (HealthCheckConstants.ERROR_RESPONSE_TIME_MS, errorMessage); | ||
| } | ||
|
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| return (HealthCheckConstants.ERROR_RESPONSE_TIME_MS, errorMessage); | ||
| } |
Comment on lines
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| mockHandler.Protected() | ||
| .Setup<Task<HttpResponseMessage>>( | ||
| "SendAsync", | ||
| ItExpr.Is<HttpRequestMessage>(req => | ||
| req.Method == HttpMethod.Post && | ||
| req.RequestUri == new Uri($"{BASE_DAB_URL}{runtimeConfig.McpPath}")), | ||
| ItExpr.IsAny<CancellationToken>()) |
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Why make this change?
/healthreport advertised whether MCP was enabled in itsconfigurationblock but never actually probed the MCP endpoint, so MCP outages were invisible to health monitoring.What is this change?
HealthCheckHelper— NewUpdateMcpHealthCheckResultsAsync, wired intoUpdateHealthCheckDetailsAsyncalongside the data-source/entity/embeddings checks. Runs only whenIsMcpEnabled; emits aHealthCheckResultEntrynamedmcp, tagged["mcp"], comparing response time against the default 1000 ms threshold.HttpUtilities.ExecuteMcpQueryAsync— POSTs a JSON-RPCinitializerequest toruntimeConfig.McpPathwithAccept: application/json, text/event-stream, reusing the existingCheckSanityOfUrlSSRF guard and role-header propagation.initializeis used becausetools/listrequires an active session under the Streamable HTTP transport.Utilities.CreateHttpMcpQuery— Builds the minimal initialize payload.HealthCheckConstants— Adds themcptag.Single
mcptag (mirroring the data-source check's singledata-sourcetag) rather than reusingendpoint, which is reserved for per-entity REST/GraphQL checks. The check is gated solely onIsMcpEnabledwith a default threshold — no new config surface.How was this tested?
ComprehensiveHealthEndpoint_ValidateContentsto assert themcptag appears iff MCP is enabled.TestHealthCheckMcpResponseAsync/TestFailureHealthCheckMcpResponseAsynccover success and non-2xx responses.Sample Request(s)
Resulting check entry when MCP is enabled:
{ "name": "mcp", "status": "Healthy", "tags": ["mcp"], "data": { "duration-ms": 12, "threshold-ms": 1000 } }