1package agent
2
3import (
4 "cmp"
5 "context"
6 "encoding/json"
7 "fmt"
8 "log/slog"
9 "slices"
10 "strings"
11 "sync"
12 "time"
13
14 "github.com/charmbracelet/crush/internal/config"
15 "github.com/charmbracelet/crush/internal/csync"
16 "github.com/charmbracelet/crush/internal/llm/tools"
17 "github.com/charmbracelet/crush/internal/permission"
18 "github.com/charmbracelet/crush/internal/pubsub"
19 "github.com/charmbracelet/crush/internal/version"
20 "github.com/mark3labs/mcp-go/client"
21 "github.com/mark3labs/mcp-go/client/transport"
22 "github.com/mark3labs/mcp-go/mcp"
23)
24
25// MCPState represents the current state of an MCP client
26type MCPState int
27
28const (
29 MCPStateDisabled MCPState = iota
30 MCPStateStarting
31 MCPStateConnected
32 MCPStateError
33)
34
35func (s MCPState) String() string {
36 switch s {
37 case MCPStateDisabled:
38 return "disabled"
39 case MCPStateStarting:
40 return "starting"
41 case MCPStateConnected:
42 return "connected"
43 case MCPStateError:
44 return "error"
45 default:
46 return "unknown"
47 }
48}
49
50// MCPEventType represents the type of MCP event
51type MCPEventType string
52
53const (
54 MCPEventStateChanged MCPEventType = "state_changed"
55)
56
57// MCPEvent represents an event in the MCP system
58type MCPEvent struct {
59 Type MCPEventType
60 Name string
61 State MCPState
62 Error error
63 ToolCount int
64}
65
66// MCPClientInfo holds information about an MCP client's state
67type MCPClientInfo struct {
68 Name string
69 State MCPState
70 Error error
71 Client *client.Client
72 ToolCount int
73 ConnectedAt time.Time
74}
75
76var (
77 mcpToolsOnce sync.Once
78 mcpTools []tools.BaseTool
79 mcpClients = csync.NewMap[string, *client.Client]()
80 mcpStates = csync.NewMap[string, MCPClientInfo]()
81 mcpBroker = pubsub.NewBroker[MCPEvent]()
82)
83
84type McpTool struct {
85 mcpName string
86 tool mcp.Tool
87 permissions permission.Service
88 workingDir string
89}
90
91func (b *McpTool) Name() string {
92 return fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name)
93}
94
95func (b *McpTool) Info() tools.ToolInfo {
96 required := b.tool.InputSchema.Required
97 if required == nil {
98 required = make([]string, 0)
99 }
100 return tools.ToolInfo{
101 Name: fmt.Sprintf("mcp_%s_%s", b.mcpName, b.tool.Name),
102 Description: b.tool.Description,
103 Parameters: b.tool.InputSchema.Properties,
104 Required: required,
105 }
106}
107
108func runTool(ctx context.Context, name, toolName string, input string) (tools.ToolResponse, error) {
109 var args map[string]any
110 if err := json.Unmarshal([]byte(input), &args); err != nil {
111 return tools.NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
112 }
113 c, ok := mcpClients.Get(name)
114 if !ok {
115 return tools.NewTextErrorResponse("mcp '" + name + "' not available"), nil
116 }
117 result, err := c.CallTool(ctx, mcp.CallToolRequest{
118 Params: mcp.CallToolParams{
119 Name: toolName,
120 Arguments: args,
121 },
122 })
123 if err != nil {
124 return tools.NewTextErrorResponse(err.Error()), nil
125 }
126
127 output := make([]string, 0, len(result.Content))
128 for _, v := range result.Content {
129 if v, ok := v.(mcp.TextContent); ok {
130 output = append(output, v.Text)
131 } else {
132 output = append(output, fmt.Sprintf("%v", v))
133 }
134 }
135 return tools.NewTextResponse(strings.Join(output, "\n")), nil
136}
137
138func (b *McpTool) Run(ctx context.Context, params tools.ToolCall) (tools.ToolResponse, error) {
139 sessionID, messageID := tools.GetContextValues(ctx)
140 if sessionID == "" || messageID == "" {
141 return tools.ToolResponse{}, fmt.Errorf("session ID and message ID are required for creating a new file")
142 }
143 permissionDescription := fmt.Sprintf("execute %s with the following parameters: %s", b.Info().Name, params.Input)
144 p := b.permissions.Request(
145 permission.CreatePermissionRequest{
146 SessionID: sessionID,
147 ToolCallID: params.ID,
148 Path: b.workingDir,
149 ToolName: b.Info().Name,
150 Action: "execute",
151 Description: permissionDescription,
152 Params: params.Input,
153 },
154 )
155 if !p {
156 return tools.ToolResponse{}, permission.ErrorPermissionDenied
157 }
158
159 return runTool(ctx, b.mcpName, b.tool.Name, params.Input)
160}
161
162func getTools(ctx context.Context, name string, permissions permission.Service, c *client.Client, workingDir string) []tools.BaseTool {
163 result, err := c.ListTools(ctx, mcp.ListToolsRequest{})
164 if err != nil {
165 slog.Error("error listing tools", "error", err)
166 updateMCPState(name, MCPStateError, err, nil, 0)
167 c.Close()
168 mcpClients.Del(name)
169 return nil
170 }
171 mcpTools := make([]tools.BaseTool, 0, len(result.Tools))
172 for _, tool := range result.Tools {
173 mcpTools = append(mcpTools, &McpTool{
174 mcpName: name,
175 tool: tool,
176 permissions: permissions,
177 workingDir: workingDir,
178 })
179 }
180 return mcpTools
181}
182
183// SubscribeMCPEvents returns a channel for MCP events
184func SubscribeMCPEvents(ctx context.Context) <-chan pubsub.Event[MCPEvent] {
185 return mcpBroker.Subscribe(ctx)
186}
187
188// GetMCPStates returns the current state of all MCP clients
189func GetMCPStates() map[string]MCPClientInfo {
190 states := make(map[string]MCPClientInfo)
191 for name, info := range mcpStates.Seq2() {
192 states[name] = info
193 }
194 return states
195}
196
197// GetMCPState returns the state of a specific MCP client
198func GetMCPState(name string) (MCPClientInfo, bool) {
199 return mcpStates.Get(name)
200}
201
202// updateMCPState updates the state of an MCP client and publishes an event
203func updateMCPState(name string, state MCPState, err error, client *client.Client, toolCount int) {
204 info := MCPClientInfo{
205 Name: name,
206 State: state,
207 Error: err,
208 Client: client,
209 ToolCount: toolCount,
210 }
211 if state == MCPStateConnected {
212 info.ConnectedAt = time.Now()
213 }
214 mcpStates.Set(name, info)
215
216 // Publish state change event
217 mcpBroker.Publish(pubsub.UpdatedEvent, MCPEvent{
218 Type: MCPEventStateChanged,
219 Name: name,
220 State: state,
221 Error: err,
222 ToolCount: toolCount,
223 })
224}
225
226// CloseMCPClients closes all MCP clients. This should be called during application shutdown.
227func CloseMCPClients() {
228 for c := range mcpClients.Seq() {
229 _ = c.Close()
230 }
231 mcpBroker.Shutdown()
232}
233
234var mcpInitRequest = mcp.InitializeRequest{
235 Params: mcp.InitializeParams{
236 ProtocolVersion: mcp.LATEST_PROTOCOL_VERSION,
237 ClientInfo: mcp.Implementation{
238 Name: "Crush",
239 Version: version.Version,
240 },
241 },
242}
243
244func doGetMCPTools(ctx context.Context, permissions permission.Service, cfg *config.Config) []tools.BaseTool {
245 var wg sync.WaitGroup
246 result := csync.NewSlice[tools.BaseTool]()
247
248 // Initialize states for all configured MCPs
249 for name, m := range cfg.MCP {
250 if m.Disabled {
251 updateMCPState(name, MCPStateDisabled, nil, nil, 0)
252 slog.Debug("skipping disabled mcp", "name", name)
253 continue
254 }
255
256 // Set initial starting state
257 updateMCPState(name, MCPStateStarting, nil, nil, 0)
258
259 wg.Add(1)
260 go func(name string, m config.MCPConfig) {
261 defer func() {
262 wg.Done()
263 if r := recover(); r != nil {
264 var err error
265 switch v := r.(type) {
266 case error:
267 err = v
268 case string:
269 err = fmt.Errorf("panic: %s", v)
270 default:
271 err = fmt.Errorf("panic: %v", v)
272 }
273 updateMCPState(name, MCPStateError, err, nil, 0)
274 slog.Error("panic in mcp client initialization", "error", err, "name", name)
275 }
276 }()
277
278 timeout := time.Duration(cmp.Or(m.Timeout, 15)) * time.Second
279 ctx, cancel := context.WithTimeout(ctx, timeout)
280 defer cancel()
281 c, err := createMcpClient(m)
282 if err != nil {
283 updateMCPState(name, MCPStateError, err, nil, 0)
284 slog.Error("error creating mcp client", "error", err, "name", name)
285 return
286 }
287 // Only call Start() for non-stdio clients, as stdio clients auto-start
288 if m.Type != config.MCPStdio {
289 if err := c.Start(ctx); err != nil {
290 updateMCPState(name, MCPStateError, err, nil, 0)
291 slog.Error("error starting mcp client", "error", err, "name", name)
292 _ = c.Close()
293 return
294 }
295 }
296 if _, err := c.Initialize(ctx, mcpInitRequest); err != nil {
297 updateMCPState(name, MCPStateError, err, nil, 0)
298 slog.Error("error initializing mcp client", "error", err, "name", name)
299 _ = c.Close()
300 return
301 }
302
303 slog.Info("Initialized mcp client", "name", name)
304 mcpClients.Set(name, c)
305
306 tools := getTools(ctx, name, permissions, c, cfg.WorkingDir())
307 updateMCPState(name, MCPStateConnected, nil, c, len(tools))
308 result.Append(tools...)
309 }(name, m)
310 }
311 wg.Wait()
312 return slices.Collect(result.Seq())
313}
314
315func createMcpClient(m config.MCPConfig) (*client.Client, error) {
316 switch m.Type {
317 case config.MCPStdio:
318 return client.NewStdioMCPClientWithOptions(
319 m.Command,
320 m.ResolvedEnv(),
321 m.Args,
322 transport.WithCommandLogger(mcpLogger{}),
323 )
324 case config.MCPHttp:
325 return client.NewStreamableHttpClient(
326 m.URL,
327 transport.WithHTTPHeaders(m.ResolvedHeaders()),
328 transport.WithHTTPLogger(mcpLogger{}),
329 )
330 case config.MCPSse:
331 return client.NewSSEMCPClient(
332 m.URL,
333 client.WithHeaders(m.ResolvedHeaders()),
334 transport.WithSSELogger(mcpLogger{}),
335 )
336 default:
337 return nil, fmt.Errorf("unsupported mcp type: %s", m.Type)
338 }
339}
340
341// for MCP's clients.
342type mcpLogger struct{}
343
344func (l mcpLogger) Errorf(format string, v ...any) { slog.Error(fmt.Sprintf(format, v...)) }
345func (l mcpLogger) Infof(format string, v ...any) { slog.Info(fmt.Sprintf(format, v...)) }