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