feat(mcp): add gog mcp subcommand with gog_exec tool

go.mod

@@ -1,17 +1,21 @@
 module github.com/steipete/gogcli
 
-go 1.26.2
+go 1.25.9
+
+toolchain go1.26.2
 
 require (
 	filippo.io/age v1.3.1
 	github.com/99designs/keyring v1.2.2
 	github.com/alecthomas/kong v1.15.0
+	github.com/mark3labs/mcp-go v0.54.0
 	github.com/muesli/termenv v0.16.0
 	github.com/stretchr/testify v1.11.1
 	github.com/yosuke-furukawa/json5 v0.1.1
 	github.com/yuin/goldmark v1.8.2
 	golang.org/x/net v0.53.0
 	golang.org/x/oauth2 v0.36.0
+	golang.org/x/sys v0.43.0
 	golang.org/x/term v0.42.0
 	golang.org/x/text v0.36.0
 	google.golang.org/api v0.277.0
@@ -33,6 +37,7 @@ require (
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/godbus/dbus v0.0.0-20190726142602-4481cbc300e2 // indirect
+	github.com/google/jsonschema-go v0.4.2 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.15 // indirect
@@ -43,15 +48,17 @@ require (
 	github.com/mtibben/percent v0.2.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2 // indirect
+	github.com/spf13/cast v1.7.1 // indirect
 	github.com/stretchr/objx v0.5.3 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.68.0 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0 // indirect
 	go.opentelemetry.io/otel v1.43.0 // indirect
 	go.opentelemetry.io/otel/metric v1.43.0 // indirect
 	go.opentelemetry.io/otel/trace v1.43.0 // indirect
 	golang.org/x/crypto v0.50.0 // indirect
-	golang.org/x/sys v0.43.0 // indirect
 	google.golang.org/genproto v0.0.0-20260414002931-afd174a4e478 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20260414002931-afd174a4e478 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260427160629-7cedc36a6bc4 // indirect

go.sum

@@ -43,6 +43,8 @@ github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek
 github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/google/jsonschema-go v0.4.2 h1:tmrUohrwoLZZS/P3x7ex0WAVknEkBZM46iALbcqoRA8=
+github.com/google/jsonschema-go v0.4.2/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
 github.com/google/s2a-go v0.1.9 h1:LGD7gtMgezd8a/Xak7mEWL0PjoTQFvpRudN895yqKW0=
 github.com/google/s2a-go v0.1.9/go.mod h1:YA0Ei2ZQL3acow2O62kdp9UlnvMmU7kA6Eutn0dXayM=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
@@ -63,6 +65,8 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/lucasb-eyer/go-colorful v1.4.0 h1:UtrWVfLdarDgc44HcS7pYloGHJUjHV/4FwW4TvVgFr4=
 github.com/lucasb-eyer/go-colorful v1.4.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
+github.com/mark3labs/mcp-go v0.54.0 h1:PZhQvd+5xrT43cUoiaKn/hDcvLUhcLc1twSEKYPTcTA=
+github.com/mark3labs/mcp-go v0.54.0/go.mod h1:+8WclSK1ZUweCP3hvktSji8n8ABG/95QaEkeVE/Uwas=
 github.com/mattn/go-isatty v0.0.22 h1:j8l17JJ9i6VGPUFUYoTUKPSgKe/83EYU2zBC7YNKMw4=
 github.com/mattn/go-isatty v0.0.22/go.mod h1:ZXfXG4SQHsB/w3ZeOYbR0PrPwLy+n6xiMrJlRFqopa4=
 github.com/mtibben/percent v0.2.1 h1:5gssi8Nqo8QU/r2pynCm+hBQHpkB/uNK7BJCFogWdzs=
@@ -76,10 +80,16 @@ github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/santhosh-tekuri/jsonschema/v6 v6.0.2 h1:KRzFb2m7YtdldCEkzs6KqmJw4nqEVZGK7IN2kJkjTuQ=
+github.com/santhosh-tekuri/jsonschema/v6 v6.0.2/go.mod h1:JXeL+ps8p7/KNMjDQk3TCwPpBy0wYklyWTfbkIzdIFU=
+github.com/spf13/cast v1.7.1 h1:cuNEagBQEHWN1FnbGEjCXL2szYEXqfJPbP2HNUaca9Y=
+github.com/spf13/cast v1.7.1/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
 github.com/stretchr/objx v0.5.3 h1:jmXUvGomnU1o3W/V5h2VEradbpJDwGrzugQQvL0POH4=
 github.com/stretchr/objx v0.5.3/go.mod h1:rDQraq+vQZU7Fde9LOZLr8Tax6zZvy4kuNKF+QYS+U0=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
+github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 github.com/yosuke-furukawa/json5 v0.1.1 h1:0F9mNwTvOuDNH243hoPqvf+dxa5QsKnZzU20uNsh3ZI=
 github.com/yosuke-furukawa/json5 v0.1.1/go.mod h1:sw49aWDqNdRJ6DYUtIQiaA3xyj2IL9tjeNYmX2ixwcU=
 github.com/yuin/goldmark v1.8.2 h1:kEGpgqJXdgbkhcOgBxkC0X0PmoPG1ZyoZ117rDVp4zE=

internal/cmd/gmail_messages.go

@@ -25,7 +25,8 @@ type GmailMessagesCmd struct {
 }
 
 type GmailMessagesSearchCmd struct {
-	Query       []string `arg:"" name:"query" help:"Search query"`
+	Query       []string `arg:"" optional:"" name:"query" help:"Search query (default: in:inbox)"`
+	QueryFlag   string   `name:"query" short:"q" help:"Search query (alias for the positional argument)"`
 	Max         int64    `name:"max" aliases:"limit" help:"Max results" default:"10"`
 	Page        string   `name:"page" aliases:"cursor" help:"Page token"`
 	All         bool     `name:"all" aliases:"all-pages,allpages" help:"Fetch all pages"`
@@ -48,7 +49,10 @@ func (c *GmailMessagesSearchCmd) Run(ctx context.Context, flags *RootFlags) erro
 	}
 	query := strings.TrimSpace(strings.Join(c.Query, " "))
 	if query == "" {
-		return usage("missing query")
+		query = strings.TrimSpace(c.QueryFlag)
+	}
+	if query == "" {
+		query = "in:inbox"
 	}
 
 	svc, err := newGmailService(ctx, account)

internal/cmd/gmail_search.go

@@ -12,7 +12,8 @@ import (
 )
 
 type GmailSearchCmd struct {
-	Query     []string `arg:"" name:"query" help:"Search query"`
+	Query     []string `arg:"" optional:"" name:"query" help:"Search query (default: in:inbox)"`
+	QueryFlag string   `name:"query" short:"q" help:"Search query (alias for the positional argument)"`
 	Max       int64    `name:"max" aliases:"limit" help:"Max results" default:"10"`
 	Page      string   `name:"page" aliases:"cursor" help:"Page token"`
 	All       bool     `name:"all" aliases:"all-pages,allpages" help:"Fetch all pages"`
@@ -30,7 +31,10 @@ func (c *GmailSearchCmd) Run(ctx context.Context, flags *RootFlags) error {
 	}
 	query := strings.TrimSpace(strings.Join(c.Query, " "))
 	if query == "" {
-		return usage("missing query")
+		query = strings.TrimSpace(c.QueryFlag)
+	}
+	if query == "" {
+		query = "in:inbox"
 	}
 
 	svc, err := newGmailService(ctx, account)

internal/cmd/mcp.go

@@ -0,0 +1,129 @@
+package cmd
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
+)
+
+// McpCmd runs an MCP server over stdio, exposing gog functionality to AI agents.
+type McpCmd struct{}
+
+const (
+	mcpMaxOutputBytes = 100 * 1024 // 100 KB
+	mcpExecTimeout    = 60 * time.Second
+)
+
+// mcpChildSafetyArgs returns global argv fragments that must be appended after
+// user-supplied args for every gog_exec subprocess. Kong resolves duplicate
+// flags last-wins, so placing safety flags last prevents MCP clients from
+// overriding restrictions.
+func mcpChildSafetyArgs(flags *RootFlags) []string {
+	if flags == nil {
+		return nil
+	}
+	var out []string
+	if flags.GmailNoSend {
+		out = append(out, "--gmail-no-send")
+	}
+	if s := strings.TrimSpace(flags.EnableCommands); s != "" {
+		out = append(out, "--enable-commands="+s)
+	}
+	if s := strings.TrimSpace(flags.DisableCommands); s != "" {
+		out = append(out, "--disable-commands="+s)
+	}
+	return out
+}
+
+func (c *McpCmd) Run(_ context.Context, flags *RootFlags) error {
+	self, err := os.Executable()
+	if err != nil {
+		return fmt.Errorf("resolve executable: %w", err)
+	}
+
+	safetySuffix := mcpChildSafetyArgs(flags)
+
+	s := server.NewMCPServer(
+		"gog",
+		VersionString(),
+		server.WithToolCapabilities(false),
+	)
+
+	gogExec := mcp.NewTool("gog_exec",
+		mcp.WithDescription("Execute any gog subcommand and return its output. "+
+			"Pass the same arguments you would type after 'gog' on the command line. "+
+			"Example: {\"args\": [\"gmail\", \"list\"]} or {\"args\": [\"calendar\", \"events\", \"--today\"]}."),
+		mcp.WithArray("args",
+			mcp.Required(),
+			mcp.WithStringItems(),
+			mcp.Description("Subcommand and flags, e.g. [\"gmail\", \"list\", \"--limit\", \"10\"]"),
+		),
+	)
+
+	s.AddTool(gogExec, func(reqCtx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+		args, err := req.RequireStringSlice("args")
+		if err != nil {
+			return mcp.NewToolResultError(fmt.Sprintf("invalid args: %v", err)), nil
+		}
+
+		ctx, cancel := context.WithTimeout(reqCtx, mcpExecTimeout)
+		defer cancel()
+
+		childArgs := make([]string, 0, len(args)+len(safetySuffix))
+		childArgs = append(childArgs, args...)
+		childArgs = append(childArgs, safetySuffix...)
+
+		//nolint:gosec
+		cmd := exec.CommandContext(ctx, self, childArgs...)
+		var stdoutBuf, stderrBuf bytes.Buffer
+		cmd.Stdout = &stdoutBuf
+		cmd.Stderr = &stderrBuf
+
+		runErr := cmd.Run()
+
+		exitCode := 0
+		if runErr != nil {
+			if exitErr, ok := runErr.(*exec.ExitError); ok {
+				exitCode = exitErr.ExitCode()
+			} else {
+				exitCode = 1
+			}
+		}
+
+		result := map[string]any{
+			"stdout":    mcpTruncate(stdoutBuf.String(), mcpMaxOutputBytes),
+			"stderr":    mcpTruncate(stderrBuf.String(), mcpMaxOutputBytes),
+			"exit_code": exitCode,
+		}
+		b, err := json.Marshal(result)
+		if err != nil {
+			return mcp.NewToolResultError(fmt.Sprintf("marshal result: %v", err)), nil
+		}
+		return mcp.NewToolResultText(string(b)), nil
+	})
+
+	srv := server.NewStdioServer(s)
+	return srv.Listen(context.Background(), os.Stdin, os.Stdout)
+}
+
+// mcpTruncate caps s to maxBytes, appending a marker if trimmed.
+func mcpTruncate(s string, maxBytes int) string {
+	if len(s) <= maxBytes {
+		return s
+	}
+	b := []byte(s)[:maxBytes]
+	// Walk back to a valid UTF-8 boundary.
+	for len(b) > 0 && !utf8.Valid(b) {
+		b = b[:len(b)-1]
+	}
+	return string(b) + "\n... [output truncated at 100 KB]"
+}

internal/cmd/root.go

@@ -99,6 +99,7 @@ type CLI struct {
 	VersionCmd    VersionCmd            `cmd:"" name:"version" help:"Print version"`
 	Completion    CompletionCmd         `cmd:"" help:"Generate shell completion scripts"`
 	Complete      CompletionInternalCmd `cmd:"" name:"__complete" hidden:"" help:"Internal completion helper"`
+	Mcp           McpCmd                `cmd:"" name:"mcp" help:"Run an MCP server over stdio (exposes gog to AI agents)"`
 }
 
 type exitPanic struct{ code int }