feat: func mcp

.gitignore

@@ -14,6 +14,9 @@
 /pkg/functions/testdata/default_home/go
 /pkg/functions/testdata/default_home/.cache
 /pkg/functions/testdata/migrations/*/.gitignore
+/pkg/creds/auth.json
+/pkg/oci/testdata/test-links/absoluteLink
+/pkg/oci/testdata/test-links/absoluteLinkWindows
 
 # Go
 /templates/go/cloudevents/go.sum

cmd/mcp.go

@@ -1,46 +1,121 @@
 package cmd
 
 import (
-	"log"
+	"fmt"
+	"os"
+	"strconv"
 
 	"github.com/spf13/cobra"
 	"knative.dev/func/pkg/mcp"
+
+	fn "knative.dev/func/pkg/functions"
 )
 
-func NewMCPServerCmd() *cobra.Command {
+func NewMCPCmd(newClient ClientFactory) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "mcp",
-		Short: "Start MCP server",
+		Short: "Model Context Protocol (MCP) server",
 		Long: `
 NAME
-	{{rootCmdUse}} mcp - start a Model Context Protocol (MCP) server
+	{{rootCmdUse}} mcp - Model Context Protocol (MCP) server
 
 SYNOPSIS
-	{{rootCmdUse}} mcp [flags]
-
+	{{rootCmdUse}} mcp [command] [flags]
 DESCRIPTION
-	Starts a Model Context Protocol (MCP) server over standard input/output (stdio) transport.
-	This implementation aims to support tools for deploying and creating serverless functions.
-
-	Note: This command is still under development.
+	The Functions Model Context Protocol (MCP) server can be used to give
+	agents the power of Functions.
+
+	Configure your agentic client to use the MCP server with command
+	"{{rootCmdUse}} mcp start".  Then get the conversation started with
+
+	"Let's create a Function!".
+
+	By default the MCP server operates in read-only mode, allowing Function
+	creation, building, and inspection, but preventing deployment and deletion.
+	To enable full write access (deploy and delete operations), set the
+	environment variable FUNC_ENABLE_MCP_WRITE=true.
+
+	This is an experimental feature, and using an LLM to create and deploy
+	code running on your cluster requires careful supervision. Functions is
+	an inherently "mutative" tool, so enabling write mode for your LLM is
+	essentially giving (sometimes unpredictable) AI the ability to create,
+	modify, deploy, and delete Function instances on your currently connected
+	cluster.
+
+	The command "{{rootCmdUse}} mcp start" is meant to be invoked by your MCP
+	client (such as Claude Code, Cursor, VS Code, Windsurf, etc.); not run
+	directly. Configure your client of choice with a new MCP server which runs
+	this command.  For example, in Claude Code this can be accomplished with:
+	  claude mcp add func func mcp start
+	Instructions for other clients can be found at:
+	  https://github.com/knative/func/blob/main/docs/mcp-integration/integration.md
+
+AVAILABLE COMMANDS
+	start    Start the MCP server (for use by your agent)
 
 EXAMPLES
 
-	o Run an MCP server:
-		{{rootCmdUse}} mcp
+	o View this help:
+		{{rootCmdUse}} mcp --help
+`,
+	}
+
+	cmd.AddCommand(NewMCPStartCmd(newClient))
+
+	return cmd
+}
+
+func NewMCPStartCmd(newClient ClientFactory) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "start",
+		Short: "Start the MCP server",
+		Long: `
+NAME
+	{{rootCmdUse}} mcp start - start the Model Context Protocol (MCP) server
+
+SYNOPSIS
+	{{rootCmdUse}} mcp start [flags]
+
+DESCRIPTION
+	Starts the Model Context Protocol (MCP) server.
+
+	This command is designed to be invoked by MCP clients directly
+	(such as Claude Code, Claude Desktop, Cursor, VS Code, Windsurf, etc.);
+	not run directly.
+
+	Please see '{{rootCmdUse}} mcp --help' for more information.
 `,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return runMCPServer(cmd, args)
+			return runMCPStart(cmd, args, newClient)
 		},
 	}
+	// no flags at this time; future enhancements may be to allow configuring
+	// HTTP Stream vs stdio, single vs multiuser modes, etc.  For now
+	// we just use a simple gathering of options in runMCPServer.
 	return cmd
 }
 
-func runMCPServer(cmd *cobra.Command, args []string) error {
-	s := mcp.NewServer()
-	if err := s.Start(); err != nil {
-		log.Fatalf("Server error: %v", err)
-		return err
+func runMCPStart(cmd *cobra.Command, args []string, newClient ClientFactory) error {
+	// Configure write mode
+	writeEnabled := false
+	if val := os.Getenv("FUNC_ENABLE_MCP_WRITE"); val != "" {
+		parsed, err := strconv.ParseBool(val)
+		if err != nil {
+			return fmt.Errorf("FUNC_ENABLE_MCP_WRITE shuold be a boolean (true/false, 1/0, etc). Received %q", val)
+		}
+		writeEnabled = parsed
 	}
-	return nil
+
+	// Configure 'func' or 'kn func'?
+	rootCmd := cmd.Root()
+	cmdPrefix := rootCmd.Use
+
+	// Instantiate
+	client, done := newClient(ClientConfig{},
+		fn.WithMCPServer(mcp.New(mcp.WithPrefix(cmdPrefix))))
+	defer done()
+
+	// Start
+	return client.StartMCPServer(cmd.Context(), writeEnabled)
+
 }

cmd/mcp_test.go

@@ -0,0 +1,67 @@
+package cmd
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	fn "knative.dev/func/pkg/functions"
+	"knative.dev/func/pkg/mock"
+	. "knative.dev/func/pkg/testing"
+)
+
+// TestMCP_Start ensures the "mcp start" command starts the MCP server.
+func TestMCP_Start(t *testing.T) {
+	_ = FromTempDirectory(t)
+
+	server := mock.NewMCPServer()
+
+	cmd := NewMCPCmd(NewTestClient(fn.WithMCPServer(server)))
+	cmd.SetArgs([]string{"start"})
+	if err := cmd.Execute(); err != nil {
+		t.Fatal(err)
+	}
+
+	if !server.StartInvoked {
+		// Indicates a failure of the command to correctly map the request
+		// for "mcp start" to an actual invocation of the client's
+		// StartMCPServer method, or something more fundamental like failure
+		// to register the subcommand, etc.
+		t.Fatal("MCP server's start method not invoked")
+	}
+}
+
+// TestMCP_StartWriteable ensures that the server is started with write
+// enabled only when the environment variable FUNC_ENABLE_MCP_WRITE is set.
+func TestMCP_StartWriteable(t *testing.T) {
+	_ = FromTempDirectory(t)
+
+	// Ensure it defaults to off.
+	server := mock.NewMCPServer()
+	server.StartFn = func(_ context.Context, writeEnabled bool) error {
+		if writeEnabled {
+			t.Fatal("MCP server started write-enabled by default")
+		}
+		return nil
+	}
+	cmd := NewMCPCmd(NewTestClient(fn.WithMCPServer(server)))
+	cmd.SetArgs([]string{"start"})
+	if err := cmd.Execute(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure it is set to true on proper truthy value
+	_ = os.Setenv("FUNC_ENABLE_MCP_WRITE", "true")
+	server = mock.NewMCPServer()
+	server.StartFn = func(_ context.Context, writeEnabled bool) error {
+		if !writeEnabled {
+			t.Fatal("MCP server was not enabled")
+		}
+		return nil
+	}
+	cmd = NewMCPCmd(NewTestClient(fn.WithMCPServer(server)))
+	cmd.SetArgs([]string{"start"})
+	if err := cmd.Execute(); err != nil {
+		t.Fatal(err)
+	}
+}

cmd/root.go

@@ -107,18 +107,13 @@ Learn more about Knative at: https://knative.dev`, cfg.Name),
 				NewEnvironmentCmd(newClient, &cfg.Version),
 			},
 		},
-		{
-			Header: "MCP Commands:",
-			Commands: []*cobra.Command{
-				NewMCPServerCmd(),
-			},
-		},
 		{
 			Header: "Other Commands:",
 			Commands: []*cobra.Command{
 				NewCompletionCmd(),
 				NewVersionCmd(cfg.Version),
 				NewTektonClusterTasksCmd(),
+				NewMCPCmd(newClient),
 			},
 		},
 	}

docs/reference/func.md

@@ -34,7 +34,7 @@ Learn more about Knative at: https://knative.dev
 * [func invoke](func_invoke.md)	 - Invoke a local or remote function
 * [func languages](func_languages.md)	 - List available function language runtimes
 * [func list](func_list.md)	 - List deployed functions
-* [func mcp](func_mcp.md)	 - Start MCP server
+* [func mcp](func_mcp.md)	 - Model Context Protocol (MCP) server
 * [func repository](func_repository.md)	 - Manage installed template repositories
 * [func run](func_run.md)	 - Run the function locally
 * [func subscribe](func_subscribe.md)	 - Subscribe a function to events

docs/reference/func_mcp.md

@@ -1,31 +1,52 @@
 ## func mcp
 
-Start MCP server
+Model Context Protocol (MCP) server
 
 ### Synopsis
 
 
 NAME
-	func mcp - start a Model Context Protocol (MCP) server
+	func mcp - Model Context Protocol (MCP) server
 
 SYNOPSIS
-	func mcp [flags]
-
+	func mcp [command] [flags]
 DESCRIPTION
-	Starts a Model Context Protocol (MCP) server over standard input/output (stdio) transport.
-	This implementation aims to support tools for deploying and creating serverless functions.
+	The Functions Model Context Protocol (MCP) server can be used to give
+	agents the power of Functions.
 
-	Note: This command is still under development.
+	Configure your agentic client to use the MCP server with command
+	"func mcp start".  Then get the conversation started with
 
-EXAMPLES
+	"Let's create a Function!".
 
-	o Run an MCP server:
-		func mcp
+	By default the MCP server operates in read-only mode, allowing Function
+	creation, building, and inspection, but preventing deployment and deletion.
+	To enable full write access (deploy and delete operations), set the
+	environment variable FUNC_ENABLE_MCP_WRITE=true.
 
+	This is an experimental feature, and using an LLM to create and deploy
+	code running on your cluster requires careful supervision. Functions is
+	an inherently "mutative" tool, so enabling write mode for your LLM is
+	essentially giving (sometimes unpredictable) AI the ability to create,
+	modify, deploy, and delete Function instances on your currently connected
+	cluster.
+
+	The command "func mcp start" is meant to be invoked by your MCP
+	client (such as Claude Code, Cursor, VS Code, Windsurf, etc.); not run
+	directly. Configure your client of choice with a new MCP server which runs
+	this command.  For example, in Claude Code this can be accomplished with:
+	  claude mcp add func func mcp start
+	Instructions for other clients can be found at:
+	  https://github.com/knative/func/blob/main/docs/mcp-integration/integration.md
+
+AVAILABLE COMMANDS
+	start    Start the MCP server (for use by your agent)
+
+EXAMPLES
+
+	o View this help:
+		func mcp --help
 
-```
-func mcp
-```
 
 ### Options
 
@@ -36,4 +57,5 @@ func mcp
 ### SEE ALSO
 
 * [func](func.md)	 - func manages Knative Functions
+* [func mcp start](func_mcp_start.md)	 - Start the MCP server
 

docs/reference/func_mcp_start.md

@@ -0,0 +1,37 @@
+## func mcp start
+
+Start the MCP server
+
+### Synopsis
+
+
+NAME
+	func mcp start - start the Model Context Protocol (MCP) server
+
+SYNOPSIS
+	func mcp start [flags]
+
+DESCRIPTION
+	Starts the Model Context Protocol (MCP) server.
+
+	This command is designed to be invoked by MCP clients directly
+	(such as Claude Code, Claude Desktop, Cursor, VS Code, Windsurf, etc.);
+	not run directly.
+
+	Please see 'func mcp --help' for more information.
+
+
+```
+func mcp start
+```
+
+### Options
+
+```
+  -h, --help   help for start
+```
+
+### SEE ALSO
+
+* [func mcp](func_mcp.md)	 - Model Context Protocol (MCP) server
+

go.mod

@@ -39,7 +39,7 @@ require (
 	github.com/hinshun/vt10x v0.0.0-20220228203356-1ab2cad5fd82
 	github.com/manifestival/client-go-client v0.6.0
 	github.com/manifestival/manifestival v0.7.2
-	github.com/mark3labs/mcp-go v0.30.0
+	github.com/modelcontextprotocol/go-sdk v1.1.0
 	github.com/opencontainers/image-spec v1.1.1
 	github.com/openshift-pipelines/pipelines-as-code v0.31.0
 	github.com/openshift/source-to-image v1.6.0
@@ -171,6 +171,7 @@ require (
 	github.com/google/gnostic-models v0.6.9 // indirect
 	github.com/google/go-intervals v0.0.2 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
+	github.com/google/jsonschema-go v0.3.0 // indirect
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
 	github.com/gorilla/mux v1.8.1 // indirect
 	github.com/gorilla/websocket v1.5.4-0.20250319132907-e064f32e3674 // indirect