1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
package fetch
import (
"encoding/base64"
"encoding/json"
"fmt"
"io"
"net/http"
"net/url"
"strings"
"time"
"github.com/xlgmokha/mcp/pkg/mcp"
)
type FetchResult struct {
URL string `json:"url"`
Content string `json:"content"`
ContentType string `json:"content_type"`
IsBinary bool `json:"is_binary"`
}
type FetchOperations struct {
httpClient *http.Client
userAgent string
}
func NewFetchOperations() *FetchOperations {
return &FetchOperations{
httpClient: &http.Client{
Timeout: 30 * time.Second,
},
userAgent: "ModelContextProtocol/1.0 (Fetch; +https://github.com/xlgmokha/mcp)",
}
}
// New creates a new Fetch MCP server
func New() *mcp.Server {
fetch := NewFetchOperations()
builder := mcp.NewServerBuilder("mcp-fetch", "1.0.0")
builder.AddTool(mcp.NewTool("fetch", "Fetches a URL and returns the content. Text content is returned as-is, binary content is base64 encoded.", map[string]interface{}{
"type": "object",
"properties": map[string]interface{}{
"url": map[string]interface{}{
"type": "string",
"description": "URL to fetch",
"format": "uri",
},
},
"required": []string{"url"},
}, func(req mcp.CallToolRequest) (mcp.CallToolResult, error) {
urlStr, ok := req.Arguments["url"].(string)
if !ok {
return mcp.NewToolError("url is required"), nil
}
parsedURL, err := url.Parse(urlStr)
if err != nil || parsedURL.Scheme == "" || parsedURL.Host == "" {
return mcp.NewToolError("Invalid URL format"), nil
}
result, err := fetch.fetchContent(parsedURL.String())
if err != nil {
return mcp.NewToolError(err.Error()), nil
}
jsonResult, err := json.MarshalIndent(result, "", " ")
if err != nil {
return mcp.NewToolError(fmt.Sprintf("Failed to marshal result: %v", err)), nil
}
return mcp.NewToolResult(mcp.NewTextContent(string(jsonResult))), nil
}))
return builder.Build()
}
func (fetch *FetchOperations) fetchContent(urlStr string) (*FetchResult, error) {
req, err := http.NewRequest("GET", urlStr, nil)
if err != nil {
return nil, fmt.Errorf("Failed to create request: %v", err)
}
req.Header.Set("User-Agent", fetch.userAgent)
resp, err := fetch.httpClient.Do(req)
if err != nil {
return nil, fmt.Errorf("Failed to fetch URL: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode >= 400 {
return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, resp.Status)
}
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("Failed to read response body: %v", err)
}
contentType := resp.Header.Get("Content-Type")
isBinary := isBinaryContent(contentType)
var content string
if isBinary {
content = base64.StdEncoding.EncodeToString(body)
} else {
content = string(body)
}
return &FetchResult{
URL: urlStr,
Content: content,
ContentType: contentType,
IsBinary: isBinary,
}, nil
}
func isBinaryContent(contentType string) bool {
if contentType == "" {
return false
}
contentType = strings.ToLower(strings.Split(contentType, ";")[0])
textTypes := []string{
"text/",
"application/json",
"application/xml",
"application/javascript",
"application/x-javascript",
}
for _, textType := range textTypes {
if strings.HasPrefix(contentType, textType) {
return false
}
}
return true
}
|
