Model Context Protocol in OCaml
anil.recoil.org
1(** MCP - Model Context Protocol implementation *)
2
3open Jsonrpc
4
5(** Common types *)
6
7(** Roles for conversation participants *)
8module Role : sig
9 type t = [ `User | `Assistant ]
10
11 val to_string : t -> string
12 val of_string : string -> t
13
14 val yojson_of_t : t -> Json.t
15 val t_of_yojson : Json.t -> t
16end
17
18(** Progress tokens for long-running operations *)
19module ProgressToken : sig
20 type t = [ `String of string | `Int of int ]
21
22 include Json.Jsonable.S with type t := t
23end
24
25(** Request IDs *)
26module RequestId : sig
27 type t = [ `String of string | `Int of int ]
28
29 include Json.Jsonable.S with type t := t
30end
31
32(** Cursors for pagination *)
33module Cursor : sig
34 type t = string
35
36 val yojson_of_t : t -> Json.t
37 val t_of_yojson : Json.t -> t
38end
39
40(** Annotations for objects *)
41module Annotated : sig
42 type t = {
43 annotations: annotation option;
44 }
45 and annotation = {
46 audience: Role.t list option;
47 priority: float option;
48 }
49
50 val yojson_of_annotation : annotation -> Json.t
51 val annotation_of_yojson : Json.t -> annotation
52
53 val yojson_of_t : t -> Json.t
54 val t_of_yojson : Json.t -> t
55end
56
57(** Text content *)
58module TextContent : sig
59 type t = {
60 text: string;
61 annotations: Annotated.annotation option;
62 }
63
64 val yojson_of_t : t -> Json.t
65 val t_of_yojson : Json.t -> t
66end
67
68(** Image content *)
69module ImageContent : sig
70 type t = {
71 data: string;
72 mime_type: string;
73 annotations: Annotated.annotation option;
74 }
75
76 val yojson_of_t : t -> Json.t
77 val t_of_yojson : Json.t -> t
78end
79
80(** Audio content *)
81module AudioContent : sig
82 type t = {
83 data: string;
84 mime_type: string;
85 annotations: Annotated.annotation option;
86 }
87
88 val yojson_of_t : t -> Json.t
89 val t_of_yojson : Json.t -> t
90end
91
92(** Base resource contents *)
93module ResourceContents : sig
94 type t = {
95 uri: string;
96 mime_type: string option;
97 }
98
99 val yojson_of_t : t -> Json.t
100 val t_of_yojson : Json.t -> t
101end
102
103(** Text resource contents *)
104module TextResourceContents : sig
105 type t = {
106 uri: string;
107 text: string;
108 mime_type: string option;
109 }
110
111 val yojson_of_t : t -> Json.t
112 val t_of_yojson : Json.t -> t
113end
114
115(** Binary resource contents *)
116module BlobResourceContents : sig
117 type t = {
118 uri: string;
119 blob: string;
120 mime_type: string option;
121 }
122
123 val yojson_of_t : t -> Json.t
124 val t_of_yojson : Json.t -> t
125end
126
127(** Embedded resource *)
128module EmbeddedResource : sig
129 type t = {
130 resource: [ `Text of TextResourceContents.t | `Blob of BlobResourceContents.t ];
131 annotations: Annotated.annotation option;
132 }
133
134 val yojson_of_t : t -> Json.t
135 val t_of_yojson : Json.t -> t
136end
137
138(** Content type used in messages *)
139type content =
140 | Text of TextContent.t
141 | Image of ImageContent.t
142 | Audio of AudioContent.t
143 | Resource of EmbeddedResource.t
144
145val yojson_of_content : content -> Json.t
146val content_of_yojson : Json.t -> content
147
148(** Message for prompts *)
149module PromptMessage : sig
150 type t = {
151 role: Role.t;
152 content: content;
153 }
154
155 val yojson_of_t : t -> Json.t
156 val t_of_yojson : Json.t -> t
157end
158
159(** Message for sampling *)
160module SamplingMessage : sig
161 type t = {
162 role: Role.t;
163 content: [ `Text of TextContent.t | `Image of ImageContent.t | `Audio of AudioContent.t ];
164 }
165
166 val yojson_of_t : t -> Json.t
167 val t_of_yojson : Json.t -> t
168end
169
170(** Implementation information *)
171module Implementation : sig
172 type t = {
173 name: string;
174 version: string;
175 }
176
177 val yojson_of_t : t -> Json.t
178 val t_of_yojson : Json.t -> t
179end
180
181(** JSONRPC message types *)
182module JSONRPCMessage : sig
183 type notification = {
184 method_: string;
185 params: Json.t option;
186 }
187
188 type request = {
189 id: RequestId.t;
190 method_: string;
191 params: Json.t option;
192 progress_token: ProgressToken.t option;
193 }
194
195 type response = {
196 id: RequestId.t;
197 result: Json.t;
198 }
199
200 type error = {
201 id: RequestId.t;
202 code: int;
203 message: string;
204 data: Json.t option;
205 }
206
207 type t =
208 | Notification of notification
209 | Request of request
210 | Response of response
211 | Error of error
212
213 val yojson_of_notification : notification -> Json.t
214 val yojson_of_request : request -> Json.t
215 val yojson_of_response : response -> Json.t
216 val yojson_of_error : error -> Json.t
217 val yojson_of_t : t -> Json.t
218
219 val notification_of_yojson : Json.t -> notification
220 val request_of_yojson : Json.t -> request
221 val response_of_yojson : Json.t -> response
222 val error_of_yojson : Json.t -> error
223 val t_of_yojson : Json.t -> t
224
225 val create_notification : ?params:Json.t option -> method_:string -> unit -> t
226 val create_request : ?params:Json.t option -> ?progress_token:ProgressToken.t option -> id:RequestId.t -> method_:string -> unit -> t
227 val create_response : id:RequestId.t -> result:Json.t -> t
228 val create_error : id:RequestId.t -> code:int -> message:string -> ?data:Json.t option -> unit -> t
229end
230
231(** Initialize request/response *)
232module Initialize : sig
233 (** Initialize request *)
234 module Request : sig
235 type t = {
236 capabilities: Json.t; (** ClientCapabilities *)
237 client_info: Implementation.t;
238 protocol_version: string;
239 }
240
241 val yojson_of_t : t -> Json.t
242 val t_of_yojson : Json.t -> t
243
244 val create : capabilities:Json.t -> client_info:Implementation.t -> protocol_version:string -> t
245 val to_jsonrpc : id:RequestId.t -> t -> JSONRPCMessage.t
246 end
247
248 (** Initialize result *)
249 module Result : sig
250 type t = {
251 capabilities: Json.t; (** ServerCapabilities *)
252 server_info: Implementation.t;
253 protocol_version: string;
254 instructions: string option;
255 meta: Json.t option;
256 }
257
258 val yojson_of_t : t -> Json.t
259 val t_of_yojson : Json.t -> t
260
261 val create : capabilities:Json.t -> server_info:Implementation.t -> protocol_version:string -> ?instructions:string -> ?meta:Json.t -> unit -> t
262 val to_jsonrpc : id:RequestId.t -> t -> JSONRPCMessage.t
263 end
264end
265
266(** Initialized notification *)
267module Initialized : sig
268 module Notification : sig
269 type t = {
270 meta: Json.t option;
271 }
272
273 val yojson_of_t : t -> Json.t
274 val t_of_yojson : Json.t -> t
275
276 val create : ?meta:Json.t -> unit -> t
277 val to_jsonrpc : t -> JSONRPCMessage.t
278 end
279end
280
281(** Parse a JSON message into an MCP message *)
282val parse_message : Json.t -> JSONRPCMessage.t
283
284(** Create JSONRPC message helpers *)
285val create_notification : ?params:Json.t option -> method_:string -> unit -> JSONRPCMessage.t
286val create_request : ?params:Json.t option -> ?progress_token:ProgressToken.t option -> id:RequestId.t -> method_:string -> unit -> JSONRPCMessage.t
287val create_response : id:RequestId.t -> result:Json.t -> JSONRPCMessage.t
288val create_error : id:RequestId.t -> code:int -> message:string -> ?data:Json.t option -> unit -> JSONRPCMessage.t