The Universal Tool Calling Protocol (UTCP) is a modern, flexible, and scalable standard for defining and interacting with tools across a wide variety of communication protocols. It is designed to be easy to use, interoperable, and extensible, making it a powerful choice for building and consuming tool-based services.
In contrast to other protocols like MCP, UTCP places a strong emphasis on:
- Scalability: UTCP is designed to handle a large number of tools and providers without compromising performance.
- Interoperability: With support for a wide range of provider types (including HTTP, WebSockets, gRPC, and even CLI tools), UTCP can integrate with almost any existing service or infrastructure.
- Ease of Use: The protocol is built on simple, well-defined Pydantic models, making it easy for developers to implement and use.
These examples illustrate the core concepts of the UTCP client and server. They are not designed to be a single, runnable example.
Note: For complete, end-to-end runnable examples, please refer to the
examples/
directory in this repository.
Setting up a client is simple. You point it to a providers.json
file, and it handles the rest.
providers.json
This file tells the client where to find one or more UTCP Manuals (providers which return a list of tools).
[
{
"name": "cool_public_apis",
"provider_type": "http",
"url": "http://utcp.io/public-apis-manual",
"http_method": "GET"
}
]
client.py
This script initializes the client and calls a tool from the provider defined above.
import asyncio
from utcp.client import UtcpClient
async def main():
# Create a client instance. It automatically loads providers
# from the specified file path.
client = await UtcpClient.create(
config={"providers_file_path": "./providers.json"}
)
# Call a tool. The name is namespaced: `provider_name.tool_name`
result = await client.call_tool(
tool_name="cool_public_apis.example_tool",
arguments={}
)
print(result)
if __name__ == "__main__":
asyncio.run(main())
Any type of server or service can be exposed as a UTCP tool. The only requirement is that a UTCPManual
is provided to the client. This manual can be served by the tool itself or, more powerfully, by a third-party registry. This allows for wrapping existing APIs and services that are not natively UTCP-aware.
Here is a minimal example using FastAPI to serve a UTCPManual
for a tool:
server.py
from fastapi import FastAPI
app = FastAPI()
# The discovery endpoint returns the tool manual
@app.get("/utcp")
def utcp_discovery():
return {
"version": "1.0",
"tools": [
{
"name": "get_weather",
"description": "Get current weather for a location",
"inputs": {
"type": "object",
"properties": {
"location": {"type": "string"}
}
},
"outputs": {
"type": "object",
"properties": {
"temperature": {"type": "number"}
}
},
"tool_provider": {
"provider_type": "http",
"url": "https://example.com/api/weather",
"http_method": "GET"
}
}
]
}
# The actual tool endpoint
@app.get("/api/weather")
def get_weather(location: str):
return {"temperature": 22.5, "conditions": "Sunny"}
For a complete, end-to-end demonstration of how to integrate UTCP with a Large Language Model (LLM) like OpenAI, see the example in example/src/full_llm_example/openai_utcp_example.py
.
This advanced example showcases:
- Dynamic Tool Discovery: No hardcoded tool names. The client loads all available tools from the
providers.json
config. - Relevant Tool Search: For each user prompt, it uses
utcp_client.search_tools()
to find the most relevant tools for the task. - LLM-Driven Tool Calls: It instructs the OpenAI model to respond with a custom JSON format to call a tool.
- Robust Execution: It parses the LLM's response, executes the tool call via
utcp_client.call_tool()
, and sends the result back to the model for a final, human-readable answer. - Conversation History: It maintains a full conversation history for contextual, multi-turn interactions.
To run the example:
- Navigate to the
example/src/full_llm_example/
directory. - Rename
example.env
to.env
and add your OpenAI API key. - Run
python openai_utcp_example.py
.
UTCP is defined by a set of core data models that describe tools, how to connect to them (providers), and how to secure them (authentication).
For a client to use a tool, it must be provided with a UtcpManual
object. This manual contains a list of all the tools available from a provider. Depending on the provider type, this manual might be retrieved from a discovery endpoint (like an HTTP URL) or loaded from a local source (like a file for a CLI tool).
{
"version": "string",
"tools": [
{
"name": "string",
"description": "string",
"inputs": { ... },
"outputs": { ... },
"tags": ["string"],
"tool_provider": { ... }
}
]
}
version
: The version of the UTCP protocol being used.tools
: A list ofTool
objects.
Each tool is defined by the Tool
model.
{
"name": "string",
"description": "string",
"inputs": {
"type": "object",
"properties": { ... },
"required": ["string"],
"description": "string",
"title": "string"
},
"outputs": { ... },
"tags": ["string"],
"tool_provider": { ... }
}
name
: The name of the tool.description
: A human-readable description of what the tool does.inputs
: A schema defining the input parameters for the tool. This follows a simplified JSON Schema format.outputs
: A schema defining the output of the tool.tags
: A list of tags for categorizing the tool making searching for relevant tools easier.tool_provider
: TheToolProvider
object that describes how to connect to and use the tool.
UTCP supports several authentication methods to secure tool access. The auth
object within a provider's configuration specifies the authentication method to use.
Authentication using a static API key, typically sent in a request header.
{
"auth_type": "api_key",
"api_key": "YOUR_SECRET_API_KEY",
"var_name": "X-API-Key"
}
Authentication using a username and password.
{
"auth_type": "basic",
"username": "your_username",
"password": "your_password"
}
Authentication using the OAuth2 client credentials flow. The UTCP client will automatically fetch a bearer token from the token_url
and use it for subsequent requests.
{
"auth_type": "oauth2",
"token_url": "https://auth.example.com/token",
"client_id": "your_client_id",
"client_secret": "your_client_secret",
"scope": "read write"
}
Providers are at the heart of UTCP's flexibility. They define the communication protocol for a given tool. UTCP supports a wide range of provider types:
http
: RESTful HTTP/HTTPS APIsse
: Server-Sent Eventshttp_stream
: HTTP Chunked Transfer Encodingcli
: Command Line Interfacewebsocket
: WebSocket bidirectional connection (work in progress)grpc
: gRPC (Google Remote Procedure Call) (work in progress)graphql
: GraphQL query language (work in progress)tcp
: Raw TCP socket (work in progress)udp
: User Datagram Protocol (work in progress)webrtc
: Web Real-Time Communication (work in progress)mcp
: Model Context Protocol (for interoperability)text
: Local text file
Each provider type has its own specific configuration options. For example, an HttpProvider
will have a url
and an http_method
.
Below are examples of how to configure each of the supported provider types in a JSON configuration file. Where possible, the tool discovery endpoint should be /utcp
. Each tool provider should offer users their json provider configuration for the tool discovery endpoint.
For connecting to standard RESTful APIs.
{
"name": "my_rest_api",
"provider_type": "http",
"url": "https://api.example.com/utcp",
"http_method": "POST",
"content_type": "application/json",
"auth": {
"auth_type": "oauth2",
"token_url": "https://api.example.com/oauth/token",
"client_id": "your_client_id",
"client_secret": "your_client_secret"
}
}
UTCP simplifies integration with existing web services by automatically converting OpenAPI v3 specifications into UTCP tools. Instead of pointing to a UtcpManual
, the url
for an http
provider can point directly to an OpenAPI JSON specification. The OpenApiConverter
handles this conversion automatically, making it seamless to integrate thousands of existing APIs.
{
"name": "open_library_api",
"provider_type": "http",
"url": "https://openlibrary.org/dev/docs/api/openapi.json"
}
When the client registers this provider, it will fetch the OpenAPI spec from the URL, convert all defined endpoints into UTCP Tool
objects, and make them available for searching and calling.
For tools that stream data using SSE. The url
should point to the discovery endpoint.
{
"name": "live_updates_service",
"provider_type": "sse",
"url": "https://api.example.com/utcp",
"event_type": "message"
}
For tools that use HTTP chunked transfer encoding to stream data. The url
should point to the discovery endpoint.
{
"name": "streaming_data_source",
"provider_type": "http_stream",
"url": "https://api.example.com/utcp",
"http_method": "GET"
}
For wrapping local command-line tools.
{
"name": "my_cli_tool",
"provider_type": "cli",
"command_name": "my-command -utcp"
}
For tools that communicate over a WebSocket connection. Tool discovery may need to be handled via a separate HTTP endpoint.
{
"name": "realtime_chat_service",
"provider_type": "websocket",
"url": "wss://api.example.com/socket"
}
For connecting to gRPC services.
{
"name": "my_grpc_service",
"provider_type": "grpc",
"host": "grpc.example.com",
"port": 50051,
"service_name": "MyService",
"method_name": "MyMethod",
"use_ssl": true
}
For interacting with GraphQL APIs. The url
should point to the discovery endpoint.
{
"name": "my_graphql_api",
"provider_type": "graphql",
"url": "https://api.example.com/utcp",
"operation_type": "query"
}
For raw TCP socket communication.
{
"name": "raw_tcp_service",
"provider_type": "tcp",
"host": "localhost",
"port": 12345
}
For UDP socket communication.
{
"name": "udp_telemetry_service",
"provider_type": "udp",
"host": "localhost",
"port": 54321
}
For peer-to-peer communication using WebRTC.
{
"name": "p2p_data_transfer",
"provider_type": "webrtc",
"signaling_server": "https://signaling.example.com",
"peer_id": "remote-peer-id"
}
For interoperability with the Model Context Protocol (MCP). This provider can connect to MCP servers via stdio
or http
.
{
"name": "my_mcp_service",
"provider_type": "mcp",
"config": {
"mcpServers": {
"my-server": {
"transport": "http",
"url": "http://localhost:8000/mcp"
}
}
},
"auth": {
"auth_type": "oauth2",
"token_url": "http://localhost:8000/token",
"client_id": "test-client",
"client_secret": "test-secret"
}
}
For loading tool definitions from a local text file. This is useful for defining a collection of tools that may use various other providers.
{
"name": "my_local_tools",
"signaling_server": "wss://signaling.example.com",
"peer_id": "unique-peer-id"
}
For interoperability with Model Context Protocol (MCP) servers.
{
"name": "my_mcp_server",
"provider_type": "mcp",
"config": {
"mcpServers": {
"server_one": {
"command": "python",
"args": ["-m", "my_mcp_server.main"]
}
}
}
}
For loading tool definitions from a local file. This is useful for defining a collection of tools from different providers in a single place.
{
"name": "my_local_tools",
"provider_type": "text",
"file_path": "/path/to/my/tools.json"
}
UTCP supports several authentication methods, which can be configured on a per-provider basis:
- API Key:
ApiKeyAuth
- Authentication using an API key sent in a header. - Basic Auth:
BasicAuth
- Authentication using a username and password. - OAuth2:
OAuth2Auth
- Authentication using the OAuth2 protocol.
The Python UTCP client provides a robust and extensible framework for interacting with tool providers. Its architecture is designed around a few key components that work together to manage, execute, and search for tools.
UtcpClient
: The main entry point for interacting with the UTCP ecosystem. It orchestrates the registration of providers, the execution of tools, and the search for available tools.UtcpClientConfig
: A Pydantic model that defines the client's configuration. It specifies the path to the providers' configuration file (providers_file_path
) and how to load sensitive variables (e.g., from a.env
file usingload_variables_from
).ClientTransportInterface
: An abstract base class that defines the contract for all transport implementations (e.g.,HttpClientTransport
,CliTransport
). Each transport is responsible for the protocol-specific communication required to register and call tools.ToolRepository
: An abstract base class that defines the interface for storing and retrieving tools and providers. The default implementation isInMemToolRepository
, which stores everything in memory.ToolSearchStrategy
: An abstract base class for implementing different tool search algorithms. The default isTagSearchStrategy
, which scores tools based on matching tags and keywords from the tool's description.
A UtcpClient
instance is created using the asynchronous UtcpClient.create()
class method. This method initializes the client with a configuration, a tool repository, and a search strategy.
import asyncio
from utcp.client import UtcpClient
async def main():
# The client automatically loads providers from the path specified in the config
client = await UtcpClient.create(
config={
"providers_file_path": "/path/to/your/providers.json",
"load_variables_from": [{
"type": "dotenv",
"env_file_path": ".env"
}]
}
)
# ... use the client
asyncio.run(main())
During initialization, the client reads the providers.json
file, substitutes any variables (e.g., ${API_KEY}
), and registers each provider.
- Registration: The
register_tool_provider
method uses the appropriate transport to fetch the tool definitions from a provider and saves them in theToolRepository
. - Execution: The
call_tool
method finds the requested tool in the repository, retrieves its provider information, and uses the correct transport to execute the call with the given arguments. Tool names are namespaced by their provider (e.g.,my_api.get_weather
). - Deregistration: Providers can be deregistered, which removes them and their associated tools from the repository.
The search_tools
method allows you to find relevant tools based on a query. It delegates the search to the configured ToolSearchStrategy
.
tools = client.search_tools(query="get current weather in London")
for tool in tools:
print(tool.name, tool.description)
- Create a virtual environment (e.g.
conda create --name utcp python=3.10
) and enable it (conda activate utcp
) - Install required libraries (
pip install -r requirements.txt
) python -m pip install --upgrade pip
python -m build
pip install dist/utcp-<version>.tar.gz
(e.g.pip install dist/utcp-1.0.0.tar.gz
)