feat(mcp): add get_godoc tool to retrieve Go documentation using 'go doc -all'

Author: snowmerak

README.md

@@ -25,6 +25,7 @@ Lux is a tool for managing a knowledge repository (.md files) and providing it t
 - **Knowledge Search (Tools)**:
   - `search_knowledge`: Searches for a list of knowledge items based on tag matching.
   - `get_knowledge_content`: Retrieves the detailed content of a specific knowledge item by its ID.
+  - `get_godoc`: Retrieves Go documentation for a specific package, type, or function using `go doc`.
 - **Embedded Index**: The generated search index is embedded into the binary for easy distribution and deployment.
 
 ## Getting Started

pkg/mcp/godoc.go

@@ -0,0 +1,57 @@
+package mcp
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+// GoDocInput is the input schema for go doc lookup.
+type GoDocInput struct {
+	Target string `json:"target" jsonschema:"the package, function, or type to look up. e.g. 'net/http', 'net/http.Client', 'fmt.Printf'"`
+}
+
+// GoDocOutput is the output schema for go doc lookup.
+type GoDocOutput struct {
+	Content string `json:"content" jsonschema:"the documentation result from go doc"`
+}
+
+// GetGoDocTool provides documentation results by running 'go doc'.
+func GetGoDocTool(ctx context.Context, req *mcp.CallToolRequest, input GoDocInput) (
+	*mcp.CallToolResult,
+	GoDocOutput,
+	error,
+) {
+	// target이 비어있으면 에러 반환
+	if strings.TrimSpace(input.Target) == "" {
+		return &mcp.CallToolResult{
+			IsError: true,
+			Content: []mcp.Content{
+				&mcp.TextContent{
+					Text: "Target is required.",
+				},
+			},
+		}, GoDocOutput{}, nil
+	}
+
+	// go doc -all <target> 실행
+	cmd := exec.CommandContext(ctx, "go", "doc", "-all", input.Target)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return &mcp.CallToolResult{
+			IsError: true,
+			Content: []mcp.Content{
+				&mcp.TextContent{
+					Text: fmt.Sprintf("go doc failed: %s\nOutput: %s", err, string(out)),
+				},
+			},
+		}, GoDocOutput{}, nil
+	}
+
+	return nil, GoDocOutput{
+		Content: string(out),
+	}, nil
+}

pkg/mcp/server.go

@@ -104,5 +104,10 @@ func NewServer() *mcp.Server {
 		Description: "Get the full content and tags of a knowledge item by its ID.",
 	}, GetKnowledgeContentTool)
 
+	mcp.AddTool(s, &mcp.Tool{
+		Name:        "get_godoc",
+		Description: "Retrieve Go documentation for a specific package, type, or function using 'go doc -all'.",
+	}, GetGoDocTool)
+
 	return s
 }