feat: add MCP support

go.mod

@@ -18,10 +18,11 @@ require (
 	github.com/gptscript-ai/chat-completion-client v0.0.0-20250224164718-139cb4507b1d
 	github.com/gptscript-ai/cmd v0.0.0-20240802230653-326b7baf6fcb
 	github.com/gptscript-ai/go-gptscript v0.9.6-0.20250204133419-744b25b84a61
-	github.com/gptscript-ai/tui v0.0.0-20250204145344-33cd15de4cee
+	github.com/gptscript-ai/tui v0.0.0-20250419050840-5e79e16786c9
 	github.com/hexops/autogold/v2 v2.2.1
 	github.com/hexops/valast v1.4.4
 	github.com/jaytaylor/html2text v0.0.0-20230321000545-74c2419ad056
+	github.com/mark3labs/mcp-go v0.21.1
 	github.com/mholt/archives v0.1.0
 	github.com/pkoukk/tiktoken-go v0.1.7
 	github.com/pkoukk/tiktoken-go-loader v0.0.2-0.20240522064338-c17e8bc0f699
@@ -122,6 +123,7 @@ require (
 	github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	github.com/yuin/goldmark v1.5.4 // indirect
 	github.com/yuin/goldmark-emoji v1.0.2 // indirect
 	go4.org v0.0.0-20230225012048-214862532bf5 // indirect

go.sum

@@ -203,8 +203,8 @@ github.com/gptscript-ai/cmd v0.0.0-20240802230653-326b7baf6fcb h1:ky2J2CzBOskC7J
 github.com/gptscript-ai/cmd v0.0.0-20240802230653-326b7baf6fcb/go.mod h1:DJAo1xTht1LDkNYFNydVjTHd576TC7MlpsVRl3oloVw=
 github.com/gptscript-ai/go-gptscript v0.9.6-0.20250204133419-744b25b84a61 h1:QxLjsLOYlsVLPwuRkP0Q8EcAoZT1s8vU2ZBSX0+R6CI=
 github.com/gptscript-ai/go-gptscript v0.9.6-0.20250204133419-744b25b84a61/go.mod h1:/FVuLwhz+sIfsWUgUHWKi32qT0i6+IXlUlzs70KKt/Q=
-github.com/gptscript-ai/tui v0.0.0-20250204145344-33cd15de4cee h1:70PHW6Xw70yNNZ5aX936XqcMLwNmfMZpCV3FCOGKpxE=
-github.com/gptscript-ai/tui v0.0.0-20250204145344-33cd15de4cee/go.mod h1:iwHxuueg2paOak7zIg0ESBWx7A0wIHGopAratbgaPNY=
+github.com/gptscript-ai/tui v0.0.0-20250419050840-5e79e16786c9 h1:wQC8sKyeGA50WnCEG+Jo5FNRIkuX3HX8d3ubyWCCoI8=
+github.com/gptscript-ai/tui v0.0.0-20250419050840-5e79e16786c9/go.mod h1:iwHxuueg2paOak7zIg0ESBWx7A0wIHGopAratbgaPNY=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/errwrap v1.1.0 h1:OxrOeh75EUXMY8TBjag2fzXGZ40LB6IKw45YeGUDY2I=
 github.com/hashicorp/errwrap v1.1.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
@@ -270,6 +270,8 @@ github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69
 github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
+github.com/mark3labs/mcp-go v0.21.1 h1:7Ek6KPIIbMhEYHRiRIg6K6UAgNZCJaHKQp926MNr6V0=
+github.com/mark3labs/mcp-go v0.21.1/go.mod h1:KmJndYv7GIgcPVwEKJjNcbhVQ+hJGJhrCCB/9xITzpE=
 github.com/mattn/go-colorable v0.1.2/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-colorable v0.1.9/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
@@ -406,6 +408,8 @@ github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavM
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
+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/yuin/goldmark v1.3.7/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 github.com/yuin/goldmark v1.5.4 h1:2uY/xC0roWy8IBEGLgB1ywIoEJFGmRrX21YQcvGZzjU=

pkg/cli/gptscript.go

@@ -215,7 +215,7 @@ func (r *GPTScript) listTools(ctx context.Context, gptScript *gptscript.GPTScrip
 		// Don't print instructions
 		tool.Instructions = ""
 
-		lines = append(lines, tool.String())
+		lines = append(lines, tool.Print())
 	}
 	fmt.Println(strings.Join(lines, "\n---\n"))
 	return nil

pkg/engine/engine.go

@@ -11,6 +11,7 @@ import (
 	"sync"
 
 	"github.com/gptscript-ai/gptscript/pkg/counter"
+	"github.com/gptscript-ai/gptscript/pkg/mcp"
 	"github.com/gptscript-ai/gptscript/pkg/types"
 	"github.com/gptscript-ai/gptscript/pkg/version"
 )
@@ -41,6 +42,11 @@ type Engine struct {
 	RuntimeManager RuntimeManager
 	Env            []string
 	Progress       chan<- types.CompletionStatus
+	MCPRunner      MCPRunner
+}
+
+type MCPRunner interface {
+	Run(ctx context.Context, progress chan<- types.CompletionStatus, tool types.Tool, input string) (string, error)
 }
 
 type State struct {
@@ -307,6 +313,21 @@ func populateMessageParams(ctx Context, completion *types.CompletionRequest, too
 	return nil
 }
 
+func (e *Engine) runMCPInvoke(ctx Context, tool types.Tool, input string) (*Return, error) {
+	runner := e.MCPRunner
+	if runner == nil {
+		runner = mcp.DefaultRunner
+	}
+	output, err := runner.Run(ctx.Ctx, e.Progress, tool, input)
+	if err != nil {
+		return nil, fmt.Errorf("failed to run MCP invoke: %w", err)
+	}
+
+	return &Return{
+		Result: &output,
+	}, nil
+}
+
 func (e *Engine) runCommandTools(ctx Context, tool types.Tool, input string) (*Return, error) {
 	if tool.IsHTTP() {
 		return e.runHTTP(ctx, tool, input)
@@ -342,6 +363,10 @@ func (e *Engine) Start(ctx Context, input string) (ret *Return, err error) {
 		}
 	}()
 
+	if tool.IsMCPInvoke() {
+		return e.runMCPInvoke(ctx, tool, input)
+	}
+
 	if tool.IsCommand() {
 		return e.runCommandTools(ctx, tool, input)
 	}
@@ -378,6 +403,7 @@ func addUpdateSystem(ctx Context, tool types.Tool, msgs []types.CompletionMessag
 		instructions = append(instructions, context.Content)
 	}
 
+	tool.Instructions = strings.TrimPrefix(tool.Instructions, types.PromptPrefix)
 	if tool.Instructions != "" {
 		instructions = append(instructions, tool.Instructions)
 	}

pkg/loader/loader.go

@@ -20,6 +20,7 @@ import (
 	"github.com/gptscript-ai/gptscript/pkg/builtin"
 	"github.com/gptscript-ai/gptscript/pkg/cache"
 	"github.com/gptscript-ai/gptscript/pkg/hash"
+	"github.com/gptscript-ai/gptscript/pkg/mcp"
 	"github.com/gptscript-ai/gptscript/pkg/openapi"
 	"github.com/gptscript-ai/gptscript/pkg/parser"
 	"github.com/gptscript-ai/gptscript/pkg/system"
@@ -155,7 +156,23 @@ func loadOpenAPI(prg *types.Program, data []byte) *openapi3.T {
 	return openAPIDocument
 }
 
-func readTool(ctx context.Context, cache *cache.Client, prg *types.Program, base *source, targetToolName, defaultModel string) ([]types.Tool, error) {
+func processMCP(ctx context.Context, tool []types.Tool, mcpLoader MCPLoader) (result []types.Tool, _ error) {
+	for _, t := range tool {
+		if t.IsMCP() {
+			mcpTools, err := mcpLoader.Load(ctx, t)
+			if err != nil {
+				return nil, fmt.Errorf("error loading MCP tools: %w", err)
+			}
+			result = append(result, mcpTools...)
+		} else {
+			result = append(result, t)
+		}
+	}
+
+	return result, nil
+}
+
+func readTool(ctx context.Context, cache *cache.Client, mcp MCPLoader, prg *types.Program, base *source, targetToolName, defaultModel string) ([]types.Tool, error) {
 	data := base.Content
 
 	var (
@@ -212,6 +229,11 @@ func readTool(ctx context.Context, cache *cache.Client, prg *types.Program, base
 		return nil, fmt.Errorf("no tools found in %s", base)
 	}
 
+	tools, err := processMCP(ctx, tools, mcp)
+	if err != nil {
+		return nil, err
+	}
+
 	var (
 		localTools  = types.ToolSet{}
 		targetTools []types.Tool
@@ -279,17 +301,17 @@ func readTool(ctx context.Context, cache *cache.Client, prg *types.Program, base
 		localTools[strings.ToLower(tool.Name)] = tool
 	}
 
-	return linkAll(ctx, cache, prg, base, targetTools, localTools, defaultModel)
+	return linkAll(ctx, cache, mcp, prg, base, targetTools, localTools, defaultModel)
 }
 
-func linkAll(ctx context.Context, cache *cache.Client, prg *types.Program, base *source, tools []types.Tool, localTools types.ToolSet, defaultModel string) (result []types.Tool, _ error) {
+func linkAll(ctx context.Context, cache *cache.Client, mcp MCPLoader, prg *types.Program, base *source, tools []types.Tool, localTools types.ToolSet, defaultModel string) (result []types.Tool, _ error) {
 	localToolsMapping := make(map[string]string, len(tools))
 	for _, localTool := range localTools {
 		localToolsMapping[strings.ToLower(localTool.Name)] = localTool.ID
 	}
 
 	for _, tool := range tools {
-		tool, err := link(ctx, cache, prg, base, tool, localTools, localToolsMapping, defaultModel)
+		tool, err := link(ctx, cache, mcp, prg, base, tool, localTools, localToolsMapping, defaultModel)
 		if err != nil {
 			return nil, err
 		}
@@ -298,7 +320,7 @@ func linkAll(ctx context.Context, cache *cache.Client, prg *types.Program, base
 	return
 }
 
-func link(ctx context.Context, cache *cache.Client, prg *types.Program, base *source, tool types.Tool, localTools types.ToolSet, localToolsMapping map[string]string, defaultModel string) (types.Tool, error) {
+func link(ctx context.Context, cache *cache.Client, mcp MCPLoader, prg *types.Program, base *source, tool types.Tool, localTools types.ToolSet, localToolsMapping map[string]string, defaultModel string) (types.Tool, error) {
 	if existing, ok := prg.ToolSet[tool.ID]; ok {
 		return existing, nil
 	}
@@ -323,7 +345,7 @@ func link(ctx context.Context, cache *cache.Client, prg *types.Program, base *so
 				linkedTool = existing
 			} else {
 				var err error
-				linkedTool, err = link(ctx, cache, prg, base, localTool, localTools, localToolsMapping, defaultModel)
+				linkedTool, err = link(ctx, cache, mcp, prg, base, localTool, localTools, localToolsMapping, defaultModel)
 				if err != nil {
 					return types.Tool{}, fmt.Errorf("failed linking %s at %s: %w", targetToolName, base, err)
 				}
@@ -333,7 +355,7 @@ func link(ctx context.Context, cache *cache.Client, prg *types.Program, base *so
 			toolNames[targetToolName] = struct{}{}
 		} else {
 			toolName, subTool := types.SplitToolRef(targetToolName)
-			resolvedTools, err := resolve(ctx, cache, prg, base, toolName, subTool, defaultModel)
+			resolvedTools, err := resolve(ctx, cache, mcp, prg, base, toolName, subTool, defaultModel)
 			if err != nil {
 				return types.Tool{}, fmt.Errorf("failed resolving %s from %s: %w", targetToolName, base, err)
 			}
@@ -373,7 +395,7 @@ func ProgramFromSource(ctx context.Context, content, subToolName string, opts ..
 	prg := types.Program{
 		ToolSet: types.ToolSet{},
 	}
-	tools, err := readTool(ctx, opt.Cache, &prg, &source{
+	tools, err := readTool(ctx, opt.Cache, opt.MCPLoader, &prg, &source{
 		Content:  []byte(content),
 		Path:     locationPath,
 		Name:     locationName,
@@ -390,13 +412,19 @@ type Options struct {
 	Cache        *cache.Client
 	Location     string
 	DefaultModel string
+	MCPLoader    MCPLoader
+}
+
+type MCPLoader interface {
+	Load(ctx context.Context, tool types.Tool) ([]types.Tool, error)
 }
 
 func complete(opts ...Options) (result Options) {
 	for _, opt := range opts {
 		result.Cache = types.FirstSet(opt.Cache, result.Cache)
 		result.Location = types.FirstSet(opt.Location, result.Location)
 		result.DefaultModel = types.FirstSet(opt.DefaultModel, result.DefaultModel)
+		result.MCPLoader = types.FirstSet(opt.MCPLoader, result.MCPLoader)
 	}
 
 	if result.Location == "" {
@@ -407,6 +435,10 @@ func complete(opts ...Options) (result Options) {
 		result.DefaultModel = builtin.GetDefaultModel()
 	}
 
+	if result.MCPLoader == nil {
+		result.MCPLoader = mcp.DefaultLoader
+	}
+
 	return
 }
 
@@ -430,15 +462,15 @@ func Program(ctx context.Context, name, subToolName string, opts ...Options) (ty
 		Name:    name,
 		ToolSet: types.ToolSet{},
 	}
-	tools, err := resolve(ctx, opt.Cache, &prg, &source{}, name, subToolName, opt.DefaultModel)
+	tools, err := resolve(ctx, opt.Cache, opt.MCPLoader, &prg, &source{}, name, subToolName, opt.DefaultModel)
 	if err != nil {
 		return types.Program{}, err
 	}
 	prg.EntryToolID = tools[0].ID
 	return prg, nil
 }
 
-func resolve(ctx context.Context, cache *cache.Client, prg *types.Program, base *source, name, subTool, defaultModel string) ([]types.Tool, error) {
+func resolve(ctx context.Context, cache *cache.Client, mcp MCPLoader, prg *types.Program, base *source, name, subTool, defaultModel string) ([]types.Tool, error) {
 	if subTool == "" {
 		t, ok := builtin.DefaultModel(name, defaultModel)
 		if ok {
@@ -452,7 +484,7 @@ func resolve(ctx context.Context, cache *cache.Client, prg *types.Program, base
 		return nil, err
 	}
 
-	result, err := readTool(ctx, cache, prg, s, subTool, defaultModel)
+	result, err := readTool(ctx, cache, mcp, prg, s, subTool, defaultModel)
 	if err != nil {
 		return nil, err
 	}