1package mcp
2
3import (
4 "context"
5 "encoding/json"
6 "fmt"
7 "iter"
8 "log/slog"
9 "strings"
10
11 "git.secluded.site/crush/internal/csync"
12 "github.com/modelcontextprotocol/go-sdk/mcp"
13)
14
15type Tool = mcp.Tool
16
17var allTools = csync.NewMap[string, []*Tool]()
18
19// Tools returns all available MCP tools.
20func Tools() iter.Seq2[string, []*Tool] {
21 return allTools.Seq2()
22}
23
24// RunTool runs an MCP tool with the given input parameters.
25func RunTool(ctx context.Context, name, toolName string, input string) (string, error) {
26 var args map[string]any
27 if err := json.Unmarshal([]byte(input), &args); err != nil {
28 return "", fmt.Errorf("error parsing parameters: %s", err)
29 }
30
31 c, err := getOrRenewClient(ctx, name)
32 if err != nil {
33 return "", err
34 }
35 result, err := c.CallTool(ctx, &mcp.CallToolParams{
36 Name: toolName,
37 Arguments: args,
38 })
39 if err != nil {
40 return "", err
41 }
42
43 output := make([]string, 0, len(result.Content))
44 for _, v := range result.Content {
45 if vv, ok := v.(*mcp.TextContent); ok {
46 output = append(output, vv.Text)
47 } else {
48 output = append(output, fmt.Sprintf("%v", v))
49 }
50 }
51 return strings.Join(output, "\n"), nil
52}
53
54// RefreshTools gets the updated list of tools from the MCP and updates the
55// global state.
56func RefreshTools(ctx context.Context, name string) {
57 session, ok := sessions.Get(name)
58 if !ok {
59 slog.Warn("refresh tools: no session", "name", name)
60 return
61 }
62
63 tools, err := getTools(ctx, session)
64 if err != nil {
65 updateState(name, StateError, err, nil, Counts{})
66 return
67 }
68
69 updateTools(name, tools)
70
71 prev, _ := states.Get(name)
72 prev.Counts.Tools = len(tools)
73 updateState(name, StateConnected, nil, session, prev.Counts)
74}
75
76func getTools(ctx context.Context, session *mcp.ClientSession) ([]*Tool, error) {
77 // Always call ListTools to get the actual available tools.
78 // The InitializeResult Capabilities.Tools field may be an empty object {},
79 // which is valid per MCP spec, but we still need to call ListTools to discover tools.
80 result, err := session.ListTools(ctx, &mcp.ListToolsParams{})
81 if err != nil {
82 return nil, err
83 }
84 return result.Tools, nil
85}
86
87func updateTools(name string, tools []*Tool) {
88 if len(tools) == 0 {
89 allTools.Del(name)
90 return
91 }
92 allTools.Set(name, tools)
93}