feat: expose a2a agents via mcp in controller http server and migrate to mcp go-sdk #1210

supreme-gg-gg · 2026-01-14T17:58:14Z

The previous PR #1201 adds a CLI option to serve A2A agents via stdio / http transport MCP server. This PR extends this feature to the Go controller's HTTP server by adding a new /mcp route and handler for Streamable HTTP server. The MCP bridge exposes the list_agents and invoke_agent tools.

e2e test has been added using a MCP client. Manual verification was done using MCP inspector and MCP clients like Cursor as well.

This PR also migrates all usages of mark3labs/mcp-go to the new official go-sdk library from Anthropic for MCP protocol and server / client implementation. Most changes are direct and syntax-only. The only exception is that I cannot find a built-in option to set headers for transport interfaces (SSE/Streamable HTTP) in go-sdk, so I had to create a custom HTTP client to make sure these headers are set in reconciler.go

Copilot

Pull request overview

This PR extends the MCP server functionality to the Go controller's HTTP server by exposing A2A agents via a new /api/mcp endpoint. The implementation builds on PR #1201 which added CLI-based MCP serving, now bringing the same capabilities to the HTTP server with support for streamable HTTP transport.

Changes:

Added MCP handler bridging MCP protocol to A2A endpoints with session-based context management
Integrated MCP handler into HTTP server with new /api/mcp route
Added comprehensive E2E tests for MCP endpoint functionality including agent listing, invocation, and error handling

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
go/internal/mcp/mcp_handler.go	Implements MCP-to-A2A bridge with `list_agents` and `invoke_agent` tools, session management, and context tracking
go/pkg/app/app.go	Instantiates MCP handler and wires it into the HTTP server configuration
go/internal/httpserver/server.go	Adds `/api/mcp` route and conditionally mounts MCP handler
go/test/e2e/invoke_mcp_test.go	E2E tests validating MCP endpoint with agent listing, invocation, and error handling

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go/internal/mcp/mcp_handler.go

EItanya

Overally looks good to me, just some minor changes

EItanya · 2026-01-16T02:22:09Z

go/internal/httpserver/server.go

 	APIPathMemories        = "/api/memories"
 	APIPathNamespaces      = "/api/namespaces"
 	APIPathA2A             = "/api/a2a"
+	APIPathMCP             = "/api/mcp"


Typically the path for streamable HTTP mcp servers is /mcp, any reason we can't do that?

go/internal/mcp/mcp_handler.go

EItanya · 2026-01-16T02:24:51Z

go/internal/mcp/mcp_handler.go

+	httpServer    *mcpserver.StreamableHTTPServer
+	lock          sync.RWMutex
+	// Map to store context IDs per session and agent
+	contextBySessionAndAgent sync.Map


Might be worth adding a TODO that this will not work across replicas. We may be able to store any necessary data in an external store if need be. Not sure we have any data specific to MCP here though, since the A2A data is already stored.

This map is only for session "routing" so the agent using this MCP tool will have proper conversation continuation with the A2A agent by tracking the MCP context ID and the A2A context ID.

I have removed this session caching map since it won't work across replicas. The same functionality is achieved by just returning the context ID to the MCP client and most agents using it are capable of remembering the proper context id to call the A2A agent if it wants to continue the conversation. This makes the code simpler and avoids needing storage on server side.

supreme-gg-gg · 2026-01-16T16:28:53Z

Overally looks good to me, just some minor changes

Yes the changes make sense, I haven't had the time to update them will do that now

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

Copilot

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 4 comments.

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go/internal/mcp/mcp_handler.go

Copilot · 2026-01-16T23:16:10Z

go/internal/httpserver/server.go

+		s.router.PathPrefix(APIPathMCP).Handler(s.config.MCPHandler)
+	}
+
 	// Use middleware for common functionality


The MCP handler route is registered before the authentication middleware is applied (line 237). In gorilla/mux, middleware added via Use() applies to routes registered before the Use() call, but the order can be confusing. While the current code appears correct (middleware applies to all routes including MCP), this pattern is fragile. Consider either: (1) explicitly documenting that routes must be registered before middleware, or (2) applying middleware before route registration for clarity and to prevent future security issues.

Suggested change

// Use middleware for common functionality

// Use middleware for common functionality.

//

// NOTE: gorilla/mux applies middleware added via Use() to all routes

// registered on this router, including those registered *before* the Use()

// call. To avoid confusion and potential security issues where routes might

// accidentally be registered without authentication, all routes for this

// server MUST be registered above this middleware block. Do not add new

// routes below these Use() calls.

go/internal/controller/reconciler/reconciler.go

Copilot · 2026-01-16T23:16:10Z

go/test/e2e/invoke_mcp_test.go

+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()


The context with timeout is created and immediately deferred for cancellation, but then the session remains open beyond this function's scope via t.Cleanup. This means the context expires after 30 seconds while the session might still be in use. Consider using the test's context or removing the timeout to avoid premature context cancellation during test execution.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: Jet Chiang <jetjiang.ez@gmail.com>

Copilot AI review requested due to automatic review settings January 14, 2026 17:58

supreme-gg-gg requested review from EItanya, ilackarms and yuval-k as code owners January 14, 2026 17:58

Copilot started reviewing on behalf of supreme-gg-gg January 14, 2026 17:58 View session

supreme-gg-gg force-pushed the feat/mcp branch from 136619a to fa6f830 Compare January 14, 2026 17:58

supreme-gg-gg linked an issue Jan 14, 2026 that may be closed by this pull request

[FEATURE] expose kagent agents through MCP #1160

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Copilot AI reviewed Jan 14, 2026

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EItanya reviewed Jan 16, 2026

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supreme-gg-gg added 2 commits January 16, 2026 17:34

expose agents via mcp in controller http server and add test

771fbd4

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

migrate to go-sdk

61a0978

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg force-pushed the feat/mcp branch from fa6f830 to 61a0978 Compare January 16, 2026 22:34

fix go lint

9909ba4

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg changed the title ~~feat: expose a2a agents via mcp in controller http server~~ feat: expose a2a agents via mcp in controller http server and migrate to mcp go-sdk Jan 16, 2026

supreme-gg-gg requested a review from Copilot January 16, 2026 23:11

Copilot started reviewing on behalf of supreme-gg-gg January 16, 2026 23:12 View session

Copilot AI reviewed Jan 16, 2026

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supreme-gg-gg and others added 2 commits January 16, 2026 18:41

Update tool description

e1ab869

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: Jet Chiang <jetjiang.ez@gmail.com>

Update go/internal/controller/reconciler/reconciler.go

b11d384

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Signed-off-by: Jet Chiang <jetjiang.ez@gmail.com>

-	// Use middleware for common functionality
+	// Use middleware for common functionality.
+	//
+	// NOTE: gorilla/mux applies middleware added via Use() to all routes
+	// registered on this router, including those registered *before* the Use()
+	// call. To avoid confusion and potential security issues where routes might
+	// accidentally be registered without authentication, all routes for this
+	// server MUST be registered above this middleware block. Do not add new
+	// routes below these Use() calls.

		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()

feat: expose a2a agents via mcp in controller http server and migrate to mcp go-sdk #1210

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feat: expose a2a agents via mcp in controller http server and migrate to mcp go-sdk #1210

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supreme-gg-gg commented Jan 14, 2026 •

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