feat: add Coder Agents chat tools to the MCP toolsdk (#28025)

Exposes the experimental Coder Agents chats API through the MCP tool registry, so MCP clients (the hosted `/api/experimental/mcp/http` server and `coder exp mcp server`) can start and drive server-side coding agents. New tools in `codersdk/toolsdk`, all thin wrappers over existing `codersdk.ExperimentalClient` methods: | Tool | Wraps | |---|---| | `coder_create_chat` | `CreateChat` (prompt, optional org, model config, labels) | | `coder_get_chat` | `GetChat` (status, last error, last turn summary, workspace, files) | | `coder_get_chat_messages` | `GetChatMessages` (user-facing parts, chronological, cursor pagination, queued prompts) | | `coder_send_chat_message` | `CreateChatMessage` (queue or interrupt busy behavior) | | `coder_interrupt_chat` | `InterruptChat` | | `coder_archive_chat` | `UpdateChat` with `archived: true` | | `coder_list_chat_model_configs` | `ListChatModelConfigs` (enabled configs with default flag) | Both MCP servers register tools from `toolsdk.All`, so no additional wiring is needed. Responses are trimmed to what an MCP caller needs (IDs as strings, user-facing transcripts) rather than full SDK payloads. No new endpoints and no database changes. Also adds MCP [prompts](https://modelcontextprotocol.io/specification/2026-07-28/server/prompts) for the chat workflows, defined once in `codersdk/toolsdk` and registered by both servers: | Prompt | Purpose | |---|---| | `coder_agents_delegate` | delegate a task to a Coder Agents chat and monitor it to completion | | `coder_agents_check` | check the status and recent activity of an existing chat | Each prompt declares the tools its workflow needs; the stdio server skips prompts whose tools are excluded by `--allowed-tools`. Tests run the tools against a chat-enabled coderdtest instance (fake OpenAI-compatible provider plus in-process AI bridge), covering the full lifecycle, an interrupt against a blocked turn, pagination cursors, permission-dependent model config filtering, and argument validation. Prompt coverage spans SDK rendering, the hosted `prompts/list`/`prompts/get` round trip, and the stdio server including allowlist gating. > Mux created this PR on Mike's behalf.
2026-09-24 15:04:27 +08:00 · 2026-08-13 18:32:47 +02:00
parent bca5d72c1c
commit 8d4d0b35dd
11 changed files with 1290 additions and 0 deletions
@@ -732,6 +732,7 @@ func (s *mcpServer) startServer(ctx context.Context, inv *serpent.Invocation, in
 	}

 	// Register tools based on the allowlist.  Zero length means allow everything.
+	registeredTools := make(map[string]bool, len(toolsdk.All))
 	for _, tool := range toolsdk.All {
 		// Skip if not allowed.
 		if len(allowedTools) > 0 && !slices.ContainsFunc(allowedTools, func(t string) bool {
@@ -753,6 +754,18 @@ func (s *mcpServer) startServer(ctx context.Context, inv *serpent.Invocation, in
 		}

 		coderdmcp.RegisterSDKTool(mcpSrv, tool, toolDeps)
+		registeredTools[tool.Tool.Name] = true
+	}
+
+	// Skip prompts whose referenced tools are unavailable so clients are
+	// not offered workflows they cannot run.
+	for _, prompt := range toolsdk.AllPrompts {
+		if slices.ContainsFunc(prompt.RequiredTools, func(name string) bool {
+			return !registeredTools[name]
+		}) {
+			continue
+		}
+		coderdmcp.RegisterSDKPrompt(mcpSrv, prompt)
 	}

 	done := make(chan error)
@@ -22,6 +22,7 @@ import (
 	"github.com/coder/coder/v2/coderd/coderdtest"
 	"github.com/coder/coder/v2/coderd/httpapi"
 	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/codersdk/toolsdk"
 	"github.com/coder/coder/v2/testutil"
 	"github.com/coder/coder/v2/testutil/expecter"
 )
@@ -107,6 +108,21 @@ func TestExpMcpServer(t *testing.T) {
 		assert.True(t, *annotations.IdempotentHint)
 		assert.False(t, *annotations.OpenWorldHint)

+		// Prompts reference chat tools, which are excluded by this
+		// allowlist, so none may be advertised.
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":5,"method":"prompts/list"}`)
+		promptsOutput := stdout.ReadLine(ctx)
+		var promptsResponse struct {
+			Result struct {
+				Prompts []struct {
+					Name string `json:"name"`
+				} `json:"prompts"`
+			} `json:"result"`
+		}
+		err = json.Unmarshal([]byte(promptsOutput), &promptsResponse)
+		require.NoError(t, err)
+		require.Empty(t, promptsResponse.Result.Prompts, "no prompts should be advertised when their tools are excluded")
+
 		// Call the tool and ensure it works.
 		toolPayload := `{"jsonrpc":"2.0","id":3,"method":"tools/call", "params": {"name": "coder_get_authenticated_user", "arguments": {}}}`
 		stdin.WriteLine(toolPayload)
@@ -121,6 +137,134 @@ func TestExpMcpServer(t *testing.T) {
 		<-cmdDone
 	})

+	t.Run("PromptsPartialAllowlist", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := testutil.Context(t, testutil.WaitShort)
+		logger := testutil.Logger(t)
+		cancelCtx, cancel := context.WithCancel(ctx)
+		t.Cleanup(cancel)
+
+		client := coderdtest.New(t, nil)
+		_ = coderdtest.CreateFirstUser(t, client)
+		// The model-list tool is an optional suggestion in the delegate
+		// workflow, so its absence must not suppress the prompt.
+		inv, root := clitest.New(t, "exp", "mcp", "server",
+			"--allowed-tools=coder_create_chat,coder_get_chat,coder_get_chat_messages,coder_send_chat_message")
+		inv = inv.WithContext(cancelCtx)
+
+		var stdout *expecter.Expecter
+		stdout, inv.Stdout = expecter.NewPiped(t)
+		stdin := testutil.NewWriterAttachedToInvocation(t, logger.Named("stdin"), inv)
+		clitest.SetupConfig(t, client, root)
+
+		cmdDone := make(chan struct{})
+		go func() {
+			defer close(cmdDone)
+			err := inv.Run()
+			assert.NoError(t, err)
+		}()
+
+		// The SDK server enforces the MCP lifecycle, so complete the
+		// initialize handshake before listing prompts.
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}`)
+		_ = stdout.ReadLine(ctx)
+		stdin.WriteLine(`{"jsonrpc":"2.0","method":"notifications/initialized"}`)
+
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":2,"method":"prompts/list"}`)
+		output := stdout.ReadLine(ctx)
+		cancel()
+		<-cmdDone
+
+		var listResponse struct {
+			Result struct {
+				Prompts []struct {
+					Name string `json:"name"`
+				} `json:"prompts"`
+			} `json:"result"`
+		}
+		err := json.Unmarshal([]byte(output), &listResponse)
+		require.NoError(t, err)
+		foundPrompts := make([]string, 0, len(listResponse.Result.Prompts))
+		for _, prompt := range listResponse.Result.Prompts {
+			foundPrompts = append(foundPrompts, prompt.Name)
+		}
+		require.Contains(t, foundPrompts, toolsdk.PromptNameAgentsDelegate)
+		require.Contains(t, foundPrompts, toolsdk.PromptNameAgentsCheck)
+	})
+
+	t.Run("Prompts", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := testutil.Context(t, testutil.WaitShort)
+		logger := testutil.Logger(t)
+		cancelCtx, cancel := context.WithCancel(ctx)
+		t.Cleanup(cancel)
+
+		client := coderdtest.New(t, nil)
+		_ = coderdtest.CreateFirstUser(t, client)
+		inv, root := clitest.New(t, "exp", "mcp", "server")
+		inv = inv.WithContext(cancelCtx)
+
+		var stdout *expecter.Expecter
+		stdout, inv.Stdout = expecter.NewPiped(t)
+		stdin := testutil.NewWriterAttachedToInvocation(t, logger.Named("stdin"), inv)
+		clitest.SetupConfig(t, client, root)
+
+		cmdDone := make(chan struct{})
+		go func() {
+			defer close(cmdDone)
+			err := inv.Run()
+			assert.NoError(t, err)
+		}()
+
+		// The SDK server enforces the MCP lifecycle, so complete the
+		// initialize handshake before listing prompts.
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}`)
+		_ = stdout.ReadLine(ctx)
+		stdin.WriteLine(`{"jsonrpc":"2.0","method":"notifications/initialized"}`)
+
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":2,"method":"prompts/list"}`)
+		output := stdout.ReadLine(ctx)
+		var listResponse struct {
+			Result struct {
+				Prompts []struct {
+					Name string `json:"name"`
+				} `json:"prompts"`
+			} `json:"result"`
+		}
+		err := json.Unmarshal([]byte(output), &listResponse)
+		require.NoError(t, err)
+		foundPrompts := make([]string, 0, len(listResponse.Result.Prompts))
+		for _, prompt := range listResponse.Result.Prompts {
+			foundPrompts = append(foundPrompts, prompt.Name)
+		}
+		for _, prompt := range toolsdk.AllPrompts {
+			require.Contains(t, foundPrompts, prompt.Name)
+		}
+
+		stdin.WriteLine(`{"jsonrpc":"2.0","id":3,"method":"prompts/get","params":{"name":"coder_agents_delegate","arguments":{"task":"Fix the flaky test."}}}`)
+		output = stdout.ReadLine(ctx)
+		cancel()
+		<-cmdDone
+
+		var getResponse struct {
+			Result struct {
+				Messages []struct {
+					Role    string `json:"role"`
+					Content struct {
+						Text string `json:"text"`
+					} `json:"content"`
+				} `json:"messages"`
+			} `json:"result"`
+		}
+		err = json.Unmarshal([]byte(output), &getResponse)
+		require.NoError(t, err)
+		require.Len(t, getResponse.Result.Messages, 1)
+		require.Equal(t, "user", getResponse.Result.Messages[0].Role)
+		require.Contains(t, getResponse.Result.Messages[0].Content.Text, "Fix the flaky test.")
+	})
+
 	t.Run("OK", func(t *testing.T) {
 		t.Parallel()