···
4
+
(* Helper for extracting string value from JSON *)
5
+
let get_string_param json name =
8
+
(match List.assoc_opt name fields with
9
+
| Some (`String value) -> value
10
+
| _ -> raise (Failure (Printf.sprintf "Missing or invalid parameter: %s" name)))
11
+
| _ -> raise (Failure "Expected JSON object")
13
+
(* Helper for extracting integer value from JSON *)
14
+
let get_int_param json name =
17
+
(match List.assoc_opt name fields with
18
+
| Some (`Int value) -> value
19
+
| _ -> raise (Failure (Printf.sprintf "Missing or invalid parameter: %s" name)))
20
+
| _ -> raise (Failure "Expected JSON object")
22
+
(* Base64 encoding - simplified version *)
23
+
module Base64 = struct
24
+
let encode_char idx =
25
+
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".[idx]
28
+
let len = String.length s in
29
+
let result = Bytes.create (((len + 2) / 3) * 4) in
35
+
let n = Char.code s.[i] lsl 16 in
36
+
let n = if i + 1 < len then n lor (Char.code s.[i+1] lsl 8) else n in
37
+
if i + 2 < len then n lor Char.code s.[i+2] else n
39
+
Bytes.set result j (encode_char ((n lsr 18) land 63));
40
+
Bytes.set result (j+1) (encode_char ((n lsr 12) land 63));
41
+
Bytes.set result (j+2)
42
+
(if i + 1 < len then encode_char ((n lsr 6) land 63) else '=');
43
+
Bytes.set result (j+3)
44
+
(if i + 2 < len then encode_char (n land 63) else '=');
45
+
loop (i + 3) (j + 4)
47
+
Bytes.sub_string result 0 (loop 0 0)
50
+
(* Generate a random image as PPM format (simple RGB format) *)
51
+
let generate_random_image width height =
52
+
let header = Printf.sprintf "P6\n%d %d\n255\n" width height in
53
+
let data = Bytes.create (width * height * 3) in
54
+
let step = Random.int 20 + 10 in
56
+
for y = 0 to height - 1 do
57
+
for x = 0 to width - 1 do
58
+
let pattern_val = ((x / step) + (y / step)) mod 2 in
59
+
let offset = (y * width + x) * 3 in
60
+
if pattern_val = 0 then begin
61
+
(* Random bright color for checkerboard *)
62
+
let r = 150 + Random.int 100 in
63
+
let g = 150 + Random.int 100 in
64
+
let b = 150 + Random.int 100 in
65
+
Bytes.set data offset (Char.chr r);
66
+
Bytes.set data (offset + 1) (Char.chr g);
67
+
Bytes.set data (offset + 2) (Char.chr b);
70
+
let r = Random.int 100 in
71
+
let g = Random.int 100 in
72
+
let b = Random.int 100 in
73
+
Bytes.set data offset (Char.chr r);
74
+
Bytes.set data (offset + 1) (Char.chr g);
75
+
Bytes.set data (offset + 2) (Char.chr b);
80
+
(* Encode PPM data as Base64 *)
81
+
Base64.encode (header ^ Bytes.to_string data)
83
+
(* Generate a simple WAV file with sine wave *)
84
+
let generate_sine_wave_audio frequency duration =
86
+
let sample_rate = 8000 in
87
+
let num_samples = sample_rate * duration in
88
+
let header = "RIFF" ^
89
+
String.make 4 '\000' ^ (* Size placeholder *)
91
+
String.make 4 '\016' ^ (* Subchunk1 size *)
92
+
String.make 2 '\001' ^ (* Audio format = 1 (PCM) *)
93
+
String.make 2 '\001' ^ (* Num channels = 1 (mono) *)
94
+
String.make 4 (Char.chr sample_rate) ^ (* Sample rate as 4 bytes *)
95
+
String.make 4 (Char.chr (sample_rate * 2)) ^ (* Byte rate *)
96
+
String.make 2 '\002' ^ (* Block align *)
97
+
String.make 2 '\016' ^ (* Bits per sample = 16 *)
99
+
String.make 4 (Char.chr (num_samples * 2)) in (* Data size *)
101
+
(* Generate sine wave samples *)
102
+
let samples = Bytes.create (num_samples * 2) in
103
+
let amplitude = 16384.0 in (* 16-bit with headroom *)
105
+
for i = 0 to num_samples - 1 do
106
+
let t = float_of_int i /. float_of_int sample_rate in
107
+
let value = amplitude *. sin (2.0 *. Float.pi *. frequency *. t) in
108
+
let sample = int_of_float value in
110
+
(* Convert to 16-bit little-endian *)
111
+
let sample = if sample < 0 then sample + 65536 else sample in
112
+
Bytes.set samples (i * 2) (Char.chr (sample land 0xff));
113
+
Bytes.set samples (i * 2 + 1) (Char.chr ((sample lsr 8) land 0xff));
116
+
(* Encode WAV data as Base64 *)
117
+
Base64.encode (header ^ Bytes.to_string samples)
119
+
(* Create a server *)
120
+
let server = create_server
121
+
~name:"OCaml MCP Multimodal Example"
123
+
~protocol_version:"2025-03-26" () |>
125
+
(* Set default capabilities *)
126
+
configure_server server ~with_tools:true ~with_resources:true ~with_prompts:true ()
128
+
(* Define and register a multimodal tool that returns text, images, and audio *)
129
+
let _ = add_tool server
130
+
~name:"multimodal_demo"
131
+
~description:"Demonstrates multimodal content with text, image, and audio"
132
+
~schema_properties:[
133
+
("width", "integer", "Width of the generated image (pixels)");
134
+
("height", "integer", "Height of the generated image (pixels)");
135
+
("frequency", "integer", "Frequency of the generated audio tone (Hz)");
136
+
("duration", "integer", "Duration of the generated audio (seconds)");
137
+
("message", "string", "Text message to include")
139
+
~schema_required:["message"]
142
+
(* Extract parameters with defaults if not provided *)
143
+
let message = get_string_param args "message" in
144
+
let width = try get_int_param args "width" with _ -> 128 in
145
+
let height = try get_int_param args "height" with _ -> 128 in
146
+
let frequency = try get_int_param args "frequency" with _ -> 440 in
147
+
let duration = try get_int_param args "duration" with _ -> 1 in
149
+
(* Generate image and audio data *)
150
+
let image_data = generate_random_image width height in
151
+
let audio_data = generate_sine_wave_audio (float_of_int frequency) duration in
153
+
(* Create a multimodal tool result *)
154
+
create_rich_tool_result
155
+
~text:(Some message)
156
+
~image:(Some (image_data, "image/ppm"))
157
+
~audio:(Some (audio_data, "audio/wav"))
162
+
Log.error (Printf.sprintf "Error in multimodal tool: %s" msg);
163
+
create_tool_result [TextContent (Printf.sprintf "Error: %s" msg)] ~is_error:true
166
+
(* Define and register a tool for generating only images *)
167
+
let _ = add_tool server
168
+
~name:"generate_image"
169
+
~description:"Generates a random image with specified dimensions"
170
+
~schema_properties:[
171
+
("width", "integer", "Width of the generated image (pixels)");
172
+
("height", "integer", "Height of the generated image (pixels)")
174
+
~schema_required:["width"; "height"]
177
+
let width = get_int_param args "width" in
178
+
let height = get_int_param args "height" in
180
+
if width < 1 || width > 1024 || height < 1 || height > 1024 then
182
+
[TextContent "Error: Dimensions must be between 1 and 1024 pixels"]
185
+
let image_data = generate_random_image width height in
187
+
[ImageContent { data = image_data; mime_type = "image/ppm" }]
191
+
Log.error (Printf.sprintf "Error in generate_image tool: %s" msg);
192
+
create_tool_result [TextContent (Printf.sprintf "Error: %s" msg)] ~is_error:true
195
+
(* Define and register a tool for generating only audio *)
196
+
let _ = add_tool server
197
+
~name:"generate_audio"
198
+
~description:"Generates an audio tone with specified frequency and duration"
199
+
~schema_properties:[
200
+
("frequency", "integer", "Frequency of the tone in Hz (20-20000)");
201
+
("duration", "integer", "Duration of the tone in seconds (1-10)")
203
+
~schema_required:["frequency"; "duration"]
206
+
let frequency = get_int_param args "frequency" in
207
+
let duration = get_int_param args "duration" in
209
+
if frequency < 20 || frequency > 20000 then
211
+
[TextContent "Error: Frequency must be between 20Hz and 20,000Hz"]
213
+
else if duration < 1 || duration > 10 then
215
+
[TextContent "Error: Duration must be between 1 and 10 seconds"]
218
+
let audio_data = generate_sine_wave_audio (float_of_int frequency) duration in
220
+
[AudioContent { data = audio_data; mime_type = "audio/wav" }]
224
+
Log.error (Printf.sprintf "Error in generate_audio tool: %s" msg);
225
+
create_tool_result [TextContent (Printf.sprintf "Error: %s" msg)] ~is_error:true
228
+
(* Define and register a resource example with multimodal content *)
229
+
let _ = add_resource server
230
+
~uri_template:"multimodal://{name}"
231
+
~description:"Get a multimodal greeting with text, image and audio"
232
+
~mime_type:"application/json"
236
+
let greeting = Printf.sprintf "Hello, %s! Welcome to the multimodal MCP example." name in
237
+
let image_data = generate_random_image 128 128 in
238
+
let audio_data = generate_sine_wave_audio 440.0 1 in
245
+
"mimeType": "image/ppm"
249
+
"mimeType": "audio/wav"
252
+
|} greeting image_data audio_data
253
+
| _ -> Printf.sprintf {|{"error": "Invalid parameters"}|}
256
+
(* Run the server with the default scheduler *)
258
+
Random.self_init(); (* Initialize random generator *)
259
+
Eio_main.run @@ fun env ->
260
+
Mcp_server.run_server env server
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