mcp-c
About
mcp server frarmwork written in c, developing efficiently and effortlessly
Details
- License
- MIT license
Explore
- Annotate C structs to auto‑generate JSON schema definitions.
- Export function names as tool handlers via EXPORT_AS macro.
- Automatic serialization between JSON and C structs.
- Built‑in bridge code generation for tool input/output parsing.
- Supports enums, nested structs, and descriptions with DES macro.
1. write your own mcp tools under src/mcp_server
- add attributes EXPORT and EXPORT_AS(name) to the functions and structs you want to use
2. build the project, cmake -B build -S . && cmake --build ., export.cpp will generate all the tedious code for you(like tools list, bridge json to struct, etc.)
3. run the project, ./mcpc
how to use
1. write your own mcp tools undersrc/mcp_server
- add attributes EXPORT and EXPORT_AS(name) to the functions and structs you want to use
2. build the project, cmake -B build -S . && cmake --build ., export.cpp will generate all the tedious code for you(like tools list, bridge json to struct, etc.)
3. run the project, ./mcpc
quick start
1. prerequisites - vcpkg(only for windows) - cmake - clang - cJSON 2. build the project windowscmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ^
-DCMAKE_TOOLCHAIN_FILE="path/to/vcpkg/scripts/buildsystems/vcpkg.cmake" ^
-G "Ninja" ^
-DVCPKG_APPLOCAL_DEPS=ON ^
-DCMAKE_BUILD_TYPE=Release ^
-B build -S .
3. run the project
./mcpc
supported feature
1. export struct first you need to add the macro to the struct consider this file name struct.c#include "export_macro.h" //first include the export macro
typedef enum EXPORT COLOR {
RED,
GREEN,
BLUE
} COLOR;
typedef struct EXPORT_AS(cloth) cloth {
enum COLOR color DES("color of the cloth");
int size;
} cloth;
typedef struct EXPORT person {
bool isMale DES("whether is male or not male is true");
int age DES("age of the person");
char name;
cloth wearing_cloths;
} person;
after you execute export.exe struct.c
this will generate the serialize code under the src folder
generated_bridge_code.c contained the code to parse a json to object
generated_function_signatures.c contained the code of definition of the struct
the above code sample will generate a get_all_function_signatures_json function
to generate definition json like the following
{
"$defs": {
"COLOR": {
"type": "integer",
"enum": ["RED", "GREEN", "BLUE"]
},
"cloth": {
"type": "object",
"properties": {
"color": {
"$ref": "#/$defs/COLOR",
"description": "color of the cloth"
},
"size": {
"type": "integer"
}
},
"required": ["color", "size"]
},
"person": {
"type": "object",
"properties": {
"isMale": {
"type": "boolean",
"description": "whether is male or not male is true"
},
"age": {
"type": "integer",
"description": "age of the person"
},
"name": {
"type": "string"
},
"wearing_cloths": {
"$ref": "#/$defs/cloth"
}
},
"required": ["isMale", "age", "name", "wearing_cloths"]
}
},
"tools":[]
}
2. export function signature and struct via annotate
first you need to add the macro for functions and struct you need to export
consider this file name func.c
#include "export_macro.h" //first include the export macro
... //struct definition here, with the code sample in section 1
EXPORT_AS(get_color) //if the function is a handler of tool "get_color", you need to add this macro
cJSON get_color(COLOR c)
{
}
EXPORT_AS(get_person_info) //if the function is a handler of tool "get_person_info", you need to add this macro
cJSON get_person_info(person p, int id)
{
}
EXPORT_AS(tools, list) // if the function is a handler of tool "tools/list", you need to add this macro, use the comma to separate the tool name and the function name
cJSON* tools_list() {
int i = 0;
return get_all_function_signatures_json();
}
this will generate a get_all_function_signatures_json function which will return the following function signature json
{
"#def": { ... } // param type defition here
"tools": [{
"name": "tools/list",
"description": "",
"inputSchema": {
"type": "object",
"properties": {
},
"required": [],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}
}, {
"name": "get_color",
"description": "",
"inputSchema": {
"type": "object",
"properties": {
"c": {
"$ref": "#/$defs/COLOR"
}
},
"required": ["c"],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}
}, {
"name": "get_person_info",
"description": "",
"inputSchema": {
"type": "object",
"properties": {
"p": {
"$ref": "#/$defs/person"
},
"id": {
"type": "integer"
}
},
"required": ["p", "id"],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}
}]
}
3. use EXPORT for short
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