1package agent
2
3import (
4 "cmp"
5 "context"
6 "encoding/json"
7 "errors"
8 "fmt"
9 "log/slog"
10 "maps"
11 "strings"
12 "sync"
13 "time"
14
15 "github.com/charmbracelet/crush/internal/config"
16 "github.com/charmbracelet/crush/internal/csync"
17 "github.com/charmbracelet/crush/internal/home"
18 "github.com/charmbracelet/crush/internal/llm/tools"
19 "github.com/charmbracelet/crush/internal/permission"
20 "github.com/charmbracelet/crush/internal/pubsub"
21 "github.com/charmbracelet/crush/internal/version"
22 "github.com/mark3labs/mcp-go/client"
23 "github.com/mark3labs/mcp-go/client/transport"
24 "github.com/mark3labs/mcp-go/mcp"
25)
26
27// MCPState represents the current state of an MCP client
28type MCPState int
29
30const (
31 MCPStateDisabled MCPState = iota
32 MCPStateStarting
33 MCPStateConnected
34 MCPStateError
35)
36
37func (s MCPState) String() string {
38 switch s {
39 case MCPStateDisabled:
40 return "disabled"
41 case MCPStateStarting:
42 return "starting"
43 case MCPStateConnected:
44 return "connected"
45 case MCPStateError:
46 return "error"
47 default:
48 return "unknown"
49 }
50}
51
52// MCPEventType represents the type of MCP event
53type MCPEventType string
54
55const (
56 MCPEventStateChanged MCPEventType = "state_changed"
57 MCPEventToolsListChanged MCPEventType = "tools_list_changed"
58)
59
60// MCPEvent represents an event in the MCP system
61type MCPEvent struct {
62 Type MCPEventType
63 Name string
64 State MCPState
65 Error error
66 ToolCount int
67}
68
69// MCPClientInfo holds information about an MCP client's state
70type MCPClientInfo struct {
71 Name string
72 State MCPState
73 Error error
74 Client *client.Client
75 ToolCount int
76 ConnectedAt time.Time
77}
78
79var (
80 mcpToolsOnce sync.Once
81 mcpTools = csync.NewMap[string, tools.BaseTool]()
82 mcpClient2Tools = csync.NewMap[string, []tools.BaseTool]()
83 mcpClients = csync.NewMap[string, *client.Client]()
84 mcpStates = csync.NewMap[string, MCPClientInfo]()
85 mcpBroker = pubsub.NewBroker[MCPEvent]()
86)
87
88type McpTool struct {
89 mcpName string
90 tool mcp.Tool
91 permissions permission.Service
92 workingDir string
93}
94
95func (b *McpTool) Name() string {
96 return fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name)
97}
98
99func (b *McpTool) Info() tools.ToolInfo {
100 required := b.tool.InputSchema.Required
101 if required == nil {
102 required = make([]string, 0)
103 }
104 parameters := b.tool.InputSchema.Properties
105 if parameters == nil {
106 parameters = make(map[string]any)
107 }
108 return tools.ToolInfo{
109 Name: fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name),
110 Description: b.tool.Description,
111 Parameters: parameters,
112 Required: required,
113 }
114}
115
116func runTool(ctx context.Context, name, toolName string, input string) (tools.ToolResponse, error) {
117 var args map[string]any
118 if err := json.Unmarshal([]byte(input), &args); err != nil {
119 return tools.NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
120 }
121
122 c, err := getOrRenewClient(ctx, name)
123 if err != nil {
124 return tools.NewTextErrorResponse(err.Error()), nil
125 }
126 result, err := c.CallTool(ctx, mcp.CallToolRequest{
127 Params: mcp.CallToolParams{
128 Name: toolName,
129 Arguments: args,
130 },
131 })
132 if err != nil {
133 return tools.NewTextErrorResponse(err.Error()), nil
134 }
135
136 output := make([]string, 0, len(result.Content))
137 for _, v := range result.Content {
138 if v, ok := v.(mcp.TextContent); ok {
139 output = append(output, v.Text)
140 } else {
141 output = append(output, fmt.Sprintf("%v", v))
142 }
143 }
144 return tools.NewTextResponse(strings.Join(output, "\n")), nil
145}
146
147func getOrRenewClient(ctx context.Context, name string) (*client.Client, error) {
148 c, ok := mcpClients.Get(name)
149 if !ok {
150 return nil, fmt.Errorf("mcp '%s' not available", name)
151 }
152
153 cfg := config.Get()
154 m := cfg.MCP[name]
155 state, _ := mcpStates.Get(name)
156
157 timeout := mcpTimeout(m)
158 pingCtx, cancel := context.WithTimeout(ctx, timeout)
159 defer cancel()
160 err := c.Ping(pingCtx)
161 if err == nil {
162 return c, nil
163 }
164 updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, state.ToolCount)
165
166 c, err = createAndInitializeClient(ctx, name, m, cfg.Resolver())
167 if err != nil {
168 return nil, err
169 }
170
171 updateMCPState(name, MCPStateConnected, nil, c, state.ToolCount)
172 mcpClients.Set(name, c)
173 return c, nil
174}
175
176func (b *McpTool) Run(ctx context.Context, params tools.ToolCall) (tools.ToolResponse, error) {
177 sessionID, messageID := tools.GetContextValues(ctx)
178 if sessionID == "" || messageID == "" {
179 return tools.ToolResponse{}, fmt.Errorf("session ID and message ID are required for creating a new file")
180 }
181 permissionDescription := fmt.Sprintf("execute %s with the following parameters:", b.Info().Name)
182 p := b.permissions.Request(
183 permission.CreatePermissionRequest{
184 SessionID: sessionID,
185 ToolCallID: params.ID,
186 Path: b.workingDir,
187 ToolName: b.Info().Name,
188 Action: "execute",
189 Description: permissionDescription,
190 Params: params.Input,
191 },
192 )
193 if !p {
194 return tools.ToolResponse{}, permission.ErrorPermissionDenied
195 }
196
197 return runTool(ctx, b.mcpName, b.tool.Name, params.Input)
198}
199
200func getTools(ctx context.Context, name string, permissions permission.Service, c *client.Client, workingDir string) []tools.BaseTool {
201 result, err := c.ListTools(ctx, mcp.ListToolsRequest{})
202 if err != nil {
203 slog.Error("error listing tools", "error", err)
204 updateMCPState(name, MCPStateError, err, nil, 0)
205 c.Close()
206 return nil
207 }
208 mcpTools := make([]tools.BaseTool, 0, len(result.Tools))
209 for _, tool := range result.Tools {
210 mcpTools = append(mcpTools, &McpTool{
211 mcpName: name,
212 tool: tool,
213 permissions: permissions,
214 workingDir: workingDir,
215 })
216 }
217 return mcpTools
218}
219
220// SubscribeMCPEvents returns a channel for MCP events
221func SubscribeMCPEvents(ctx context.Context) <-chan pubsub.Event[MCPEvent] {
222 return mcpBroker.Subscribe(ctx)
223}
224
225// GetMCPStates returns the current state of all MCP clients
226func GetMCPStates() map[string]MCPClientInfo {
227 return maps.Collect(mcpStates.Seq2())
228}
229
230// GetMCPState returns the state of a specific MCP client
231func GetMCPState(name string) (MCPClientInfo, bool) {
232 return mcpStates.Get(name)
233}
234
235// updateMCPState updates the state of an MCP client and publishes an event
236func updateMCPState(name string, state MCPState, err error, client *client.Client, toolCount int) {
237 info := MCPClientInfo{
238 Name: name,
239 State: state,
240 Error: err,
241 Client: client,
242 ToolCount: toolCount,
243 }
244 switch state {
245 case MCPStateConnected:
246 info.ConnectedAt = time.Now()
247 case MCPStateError:
248 updateMcpTools(name, nil)
249 mcpClients.Del(name)
250 }
251 mcpStates.Set(name, info)
252
253 // Publish state change event
254 mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
255 Type: MCPEventStateChanged,
256 Name: name,
257 State: state,
258 Error: err,
259 ToolCount: toolCount,
260 })
261}
262
263// publishMCPEventToolsListChanged publishes a tool list changed event
264func publishMCPEventToolsListChanged(name string) {
265 mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
266 Type: MCPEventToolsListChanged,
267 Name: name,
268 })
269}
270
271// CloseMCPClients closes all MCP clients. This should be called during application shutdown.
272func CloseMCPClients() error {
273 var errs []error
274 for name, c := range mcpClients.Seq2() {
275 if err := c.Close(); err != nil {
276 errs = append(errs, fmt.Errorf("close mcp: %s: %w", name, err))
277 }
278 }
279 mcpBroker.Shutdown()
280 return errors.Join(errs...)
281}
282
283var mcpInitRequest = mcp.InitializeRequest{
284 Params: mcp.InitializeParams{
285 ProtocolVersion: mcp.LATEST_PROTOCOL_VERSION,
286 ClientInfo: mcp.Implementation{
287 Name: "Crush",
288 Version: version.Version,
289 },
290 },
291}
292
293func doGetMCPTools(ctx context.Context, permissions permission.Service, cfg *config.Config) {
294 var wg sync.WaitGroup
295 // Initialize states for all configured MCPs
296 for name, m := range cfg.MCP {
297 if m.Disabled {
298 updateMCPState(name, MCPStateDisabled, nil, nil, 0)
299 slog.Debug("skipping disabled mcp", "name", name)
300 continue
301 }
302
303 // Set initial starting state
304 updateMCPState(name, MCPStateStarting, nil, nil, 0)
305
306 wg.Add(1)
307 go func(name string, m config.MCPConfig) {
308 defer func() {
309 wg.Done()
310 if r := recover(); r != nil {
311 var err error
312 switch v := r.(type) {
313 case error:
314 err = v
315 case string:
316 err = fmt.Errorf("panic: %s", v)
317 default:
318 err = fmt.Errorf("panic: %v", v)
319 }
320 updateMCPState(name, MCPStateError, err, nil, 0)
321 slog.Error("panic in mcp client initialization", "error", err, "name", name)
322 }
323 }()
324
325 ctx, cancel := context.WithTimeout(ctx, mcpTimeout(m))
326 defer cancel()
327 c, err := createAndInitializeClient(ctx, name, m, cfg.Resolver())
328 if err != nil {
329 return
330 }
331
332 mcpClients.Set(name, c)
333
334 tools := getTools(ctx, name, permissions, c, cfg.WorkingDir())
335 updateMcpTools(name, tools)
336 updateMCPState(name, MCPStateConnected, nil, c, len(tools))
337 }(name, m)
338 }
339 wg.Wait()
340}
341
342// updateMcpTools updates the global mcpTools and mcpClient2Tools maps
343func updateMcpTools(mcpName string, tools []tools.BaseTool) {
344 if len(tools) == 0 {
345 mcpClient2Tools.Del(mcpName)
346 } else {
347 mcpClient2Tools.Set(mcpName, tools)
348 }
349 for _, tools := range mcpClient2Tools.Seq2() {
350 for _, t := range tools {
351 mcpTools.Set(t.Name(), t)
352 }
353 }
354}
355
356func createAndInitializeClient(ctx context.Context, name string, m config.MCPConfig, resolver config.VariableResolver) (*client.Client, error) {
357 c, err := createMcpClient(name, m, resolver)
358 if err != nil {
359 updateMCPState(name, MCPStateError, err, nil, 0)
360 slog.Error("error creating mcp client", "error", err, "name", name)
361 return nil, err
362 }
363
364 c.OnNotification(func(n mcp.JSONRPCNotification) {
365 slog.Debug("Received MCP notification", "name", name, "notification", n)
366 switch n.Method {
367 case "notifications/tools/list_changed":
368 publishMCPEventToolsListChanged(name)
369 default:
370 slog.Debug("Unhandled MCP notification", "name", name, "method", n.Method)
371 }
372 })
373
374 timeout := mcpTimeout(m)
375 initCtx, cancel := context.WithTimeout(ctx, timeout)
376 defer cancel()
377
378 if err := c.Start(ctx); err != nil {
379 updateMCPState(name, MCPStateError, err, nil, 0)
380 slog.Error("error starting mcp client", "error", err, "name", name)
381 _ = c.Close()
382 return nil, err
383 }
384
385 if _, err := c.Initialize(initCtx, mcpInitRequest); err != nil {
386 updateMCPState(name, MCPStateError, maybeTimeoutErr(err, timeout), nil, 0)
387 slog.Error("error initializing mcp client", "error", err, "name", name)
388 _ = c.Close()
389 return nil, err
390 }
391
392 slog.Info("Initialized mcp client", "name", name)
393 return c, nil
394}
395
396func maybeTimeoutErr(err error, timeout time.Duration) error {
397 if errors.Is(err, context.DeadlineExceeded) {
398 return fmt.Errorf("timed out after %s", timeout)
399 }
400 return err
401}
402
403func createMcpClient(name string, m config.MCPConfig, resolver config.VariableResolver) (*client.Client, error) {
404 switch m.Type {
405 case config.MCPStdio:
406 command, err := resolver.ResolveValue(m.Command)
407 if err != nil {
408 return nil, fmt.Errorf("invalid mcp command: %w", err)
409 }
410 if strings.TrimSpace(command) == "" {
411 return nil, fmt.Errorf("mcp stdio config requires a non-empty 'command' field")
412 }
413 return client.NewStdioMCPClientWithOptions(
414 home.Long(command),
415 m.ResolvedEnv(),
416 m.Args,
417 transport.WithCommandLogger(mcpLogger{name: name}),
418 )
419 case config.MCPHttp:
420 if strings.TrimSpace(m.URL) == "" {
421 return nil, fmt.Errorf("mcp http config requires a non-empty 'url' field")
422 }
423 return client.NewStreamableHttpClient(
424 m.URL,
425 transport.WithHTTPHeaders(m.ResolvedHeaders()),
426 transport.WithHTTPLogger(mcpLogger{name: name}),
427 )
428 case config.MCPSse:
429 if strings.TrimSpace(m.URL) == "" {
430 return nil, fmt.Errorf("mcp sse config requires a non-empty 'url' field")
431 }
432 return client.NewSSEMCPClient(
433 m.URL,
434 client.WithHeaders(m.ResolvedHeaders()),
435 transport.WithSSELogger(mcpLogger{name: name}),
436 )
437 default:
438 return nil, fmt.Errorf("unsupported mcp type: %s", m.Type)
439 }
440}
441
442// for MCP's clients.
443type mcpLogger struct{ name string }
444
445func (l mcpLogger) Errorf(format string, v ...any) {
446 slog.Error(fmt.Sprintf(format, v...), "name", l.name)
447}
448
449func (l mcpLogger) Infof(format string, v ...any) {
450 slog.Info(fmt.Sprintf(format, v...), "name", l.name)
451}
452
453func mcpTimeout(m config.MCPConfig) time.Duration {
454 return time.Duration(cmp.Or(m.Timeout, 15)) * time.Second
455}