Python Utcp

Universal Tool Calling Protocol (UTCP)

[](https://github.com/universal-tool-calling-protocol) [](https://pepy.tech/projects/utcp) [](https://github.com/universal-tool-calling-protocol/python-utcp/blob/main/LICENSE) [](https://cdtm.com/)

Introduction

The Universal Tool Calling Protocol (UTCP) is a secure, scalable standard for defining and interacting with tools across a wide variety of communication protocols. UTCP 1.0.0 introduces a modular core with a plugin-based architecture, making it more extensible, testable, and easier to package.

In contrast to other protocols, UTCP places a strong emphasis on:

• Scalability: UTCP is designed to handle a large number of tools and providers without compromising performance.
• Extensibility: A pluggable architecture allows developers to easily add new communication protocols, tool storage mechanisms, and search strategies without modifying the core library.
• Interoperability: With a growing ecosystem of protocol plugins (including HTTP, SSE, CLI, and more), 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.

Repository Structure

This repository contains the complete UTCP Python implementation:

• [core/](core/) - Core utcp package with foundational components ([README](core/README.md))
• [plugins/communication_protocols/](plugins/communication_protocols/) - Protocol-specific plugins:
• [http/](plugins/communicationprotocols/http/) - HTTP/REST, SSE, streaming, OpenAPI ([README](plugins/communicationprotocols/http/README.md))
• [cli/](plugins/communicationprotocols/cli/) - Command-line tools ([README](plugins/communicationprotocols/cli/README.md))
• [mcp/](plugins/communicationprotocols/mcp/) - Model Context Protocol ([README](plugins/communicationprotocols/mcp/README.md))
• [text/](plugins/communicationprotocols/text/) - File-based tools ([README](plugins/communicationprotocols/text/README.md))
• [socket/](plugins/communication_protocols/socket/) - TCP/UDP (🚧 In Progress)
• [gql/](plugins/communication_protocols/gql/) - GraphQL (🚧 In Progress)

Architecture Overview

UTCP uses a modular architecture with a core library and protocol plugins:

Core Package (utcp)

The [core/](core/) directory contains the foundational components:

• Data Models: Pydantic models for Tool, CallTemplate, UtcpManual, and Auth
• Client Interface: Main UtcpClient for tool interaction
• Plugin System: Extensible interfaces for protocols, repositories, and search
• Default Implementations: Built-in tool storage and search strategies

Quick Start

Installation

Install the core library and any required protocol plugins:

# Install core + HTTP plugin (most common)
pip install utcp utcp-http

# Install additional plugins as needed
pip install utcp-cli utcp-mcp utcp-text

Basic Usage

from utcp.utcp_client import UtcpClient

# Create client with HTTP API
client = await UtcpClient.create(config={
    "manual_call_templates": [{
        "name": "my_api",
        "call_template_type": "http",
        "url": "https://api.example.com/utcp"
    }]
})

# Call a tool
result = await client.call_tool("my_api.get_data", {"id": "123"})

Protocol Plugins

UTCP supports multiple communication protocols through dedicated plugins:

| Plugin | Description | Status | Documentation | |--------|-------------|--------|---------------| | [utcp-http](plugins/communicationprotocols/http/) | HTTP/REST APIs, SSE, streaming | ✅ Stable | [HTTP Plugin README](plugins/communicationprotocols/http/README.md) | | [utcp-cli](plugins/communicationprotocols/cli/) | Command-line tools | ✅ Stable | [CLI Plugin README](plugins/communicationprotocols/cli/README.md) | | [utcp-mcp](plugins/communicationprotocols/mcp/) | Model Context Protocol | ✅ Stable | [MCP Plugin README](plugins/communicationprotocols/mcp/README.md) | | [utcp-text](plugins/communicationprotocols/text/) | Local file-based tools | ✅ Stable | [Text Plugin README](plugins/communicationprotocols/text/README.md) | | [utcp-websocket](plugins/communicationprotocols/websocket/) | WebSocket real-time bidirectional communication | ✅ Stable | [WebSocket Plugin README](plugins/communicationprotocols/websocket/README.md) | | [utcp-socket](plugins/communicationprotocols/socket/) | TCP/UDP protocols | 🚧 In Progress | [Socket Plugin README](plugins/communicationprotocols/socket/README.md) | | [utcp-gql](plugins/communicationprotocols/gql/) | GraphQL APIs | 🚧 In Progress | [GraphQL Plugin README](plugins/communicationprotocols/gql/README.md) |

For development, you can install the packages in editable mode from the cloned repository:

# Clone the repository
git clone https://github.com/universal-tool-calling-protocol/python-utcp.git
cd python-utcp

# Install the core package in editable mode with dev dependencies
pip install -e "core[dev]"

# Install a specific protocol plugin in editable mode
pip install -e plugins/communication_protocols/http

Migration Guide from 0.x to 1.0.0

Version 1.0.0 introduces several breaking changes. Follow these steps to migrate your project.

1. Update Dependencies: Install the new utcp core package and the specific protocol plugins you use (e.g., utcp-http, utcp-cli).
2. Configuration:

• Configuration Object: UtcpClient is initialized with a UtcpClientConfig object, dict or a path to a JSON file containing the configuration.
• Manual Call Templates: The providers_file_path option is removed. Instead of a file path, you now provide a list of manual_call_templates directly within the UtcpClientConfig.
• Terminology: The term provider has been replaced with call_template, and provider_type is now call_template_type.
• Streamable HTTP: The call_template_type http_stream has been renamed to streamable_http.

1. Update Imports: Change your imports to reflect the new modular structure. For example, from utcp.client.transport_interfaces.http_transport import HttpProvider becomes from utcp_http.http_call_template import HttpCallTemplate.
2. Tool Search: If you were using the default search, the new strategy is TagAndDescriptionWordMatchStrategy. This is the new default and requires no changes unless you were implementing a custom strategy.
3. Tool Naming: Tool names are now namespaced as manual_name.tool_name. The client handles this automatically.
4. Variable Substitution Namespacing: Variables that are substituted in different call_templates, are first namespaced with the name of the manual with the _ duplicated. So a key in a tool call template called API_KEY from the manual manual_1 would be converted to manual__1_API_KEY.

Usage Examples

1. Using the UTCP Client

config.json (Optional)

You can define a comprehensive client configuration in a JSON file. All of these fields are optional.

{
  "variables": {
    "openlibrary_URL": "https://openlibrary.org/static/openapi.json"
  },
  "load_variables_from": [
    {
      "variable_loader_type": "dotenv",
      "env_file_path": ".env"
    }
  ],
  "tool_repository": {
    "tool_repository_type": "in_memory"
  },
  "tool_search_strategy": {
    "tool_search_strategy_type": "tag_and_description_word_match"
  },
  "manual_call_templates": [
    {
        "name": "openlibrary",
        "call_template_type": "http",
        "http_method": "GET",
        "url": "${URL}",
        "content_type": "application/json"
    },
  ],
  "post_processing": [
    {
        "tool_post_processor_type": "filter_dict",
        "only_include_keys": ["name", "key"],
        "only_include_tools": ["openlibrary.read_search_authors_json_search_authors_json_get"]
    }
  ]
}

client.py

import asyncio
from utcp.utcp_client import UtcpClient
from utcp.data.utcp_client_config import UtcpClientConfig

async def main():
    # The UtcpClient can be created with a config file path, a dict, or a UtcpClientConfig object.

    # Option 1: Initialize from a config file path
    # client_from_file = await UtcpClient.create(config="./config.json")

    # Option 2: Initialize from a dictionary
    client_from_dict = await UtcpClient.create(config={
        "variables": {
            "openlibrary_URL": "https://openlibrary.org/static/openapi.json"
        },
        "load_variables_from": [
            {
                "variable_loader_type": "dotenv",
                "env_file_path": ".env"
            }
        ],
        "tool_repository": {
            "tool_repository_type": "in_memory"
        },
        "tool_search_strategy": {
            "tool_search_strategy_type": "tag_and_description_word_match"
        },
        "manual_call_templates": [
            {
                "name": "openlibrary",
                "call_template_type": "http",
                "http_method": "GET",
                "url": "${URL}",
                "content_type": "application/json"
            }
        ],
        "post_processing": [
            {
                "tool_post_processor_type": "filter_dict",
                "only_include_keys": ["name", "key"],
                "only_include_tools": ["openlibrary.read_search_authors_json_search_authors_json_get"]
            }
        ]
    })

    # Option 3: Initialize with a full-featured UtcpClientConfig object
    from utcp_http.http_call_template import HttpCallTemplate
    from utcp.data.variable_loader import VariableLoaderSerializer
    from utcp.interfaces.tool_post_processor import ToolPostProcessorConfigSerializer

    config_obj = UtcpClientConfig(
        variables={"openlibrary_URL": "https://openlibrary.org/static/openapi.json"},
        load_variables_from=[
            VariableLoaderSerializer().validate_dict({
                "variable_loader_type": "dotenv", "env_file_path": ".env"
            })
        ],
        manual_call_templates=[
            HttpCallTemplate(
                name="openlibrary",
                call_template_type="http",
                http_method="GET",
                url="${URL}",
                content_type="application/json"
            )
        ],
        post_processing=[
            ToolPostProcessorConfigSerializer().validate_dict({
                "tool_post_processor_type": "filter_dict",
                "only_include_keys": ["name", "key"],
                "only_include_tools": ["openlibrary.read_search_authors_json_search_authors_json_get"]
            })
        ]
    )
    client = await UtcpClient.create(config=config_obj)

    # Call a tool. The name is namespaced: `manual_name.tool_name`
    result = await client.call_tool(
        tool_name="openlibrary.read_search_authors_json_search_authors_json_get",
        tool_args={"q": "J. K. Rowling"}
    )

    print(result)

if __name__ == "__main__":
    asyncio.run(main())

2. Providing a UTCP Manual

A UTCPManual describes the tools you offer. The key change is replacing tool_provider with tool_call_template.

server.py

UTCP decorator version:

from fastapi import FastAPI
from utcp_http.http_call_template import HttpCallTemplate
from utcp.data.utcp_manual import UtcpManual
from utcp.python_specific_tooling.tool_decorator import utcp_tool

app = FastAPI()

# The discovery endpoint returns the tool manual
@app.get("/utcp")
def utcp_discovery():
    return UtcpManual.create_from_decorators(manual_version="1.0.0")

# The actual tool endpoint
@utcp_tool(tool_call_template=HttpCallTemplate(
    name="get_weather",
    url=f"https://example.com/api/weather",
    http_method="GET"
), tags=["weather"])
@app.get("/api/weather")
def get_weather(location: str):
    return {"temperature": 22.5, "conditions": "Sunny"}

No UTCP dependencies server version:

from fastapi import FastAPI

app = FastAPI()

# The discovery endpoint returns the tool manual
@app.get("/utcp")
def utcp_discovery():
    return {
        "manual_version": "1.0.0",
        "utcp_version": "1.0.2",
        "tools": [
            {
                "name": "get_weather",
                "description": "Get current weather for a location",
                "tags": ["weather"],
                "inputs": {
                    "type": "object",
                    "properties": {
                        "location": {"type": "string"}
                    }
                },
                "outputs": {
                    "type": "object",
                    "properties": {
                        "temperature": {"type": "number"},
                        "conditions": {"type": "string"}
                    }
                },
                "tool_call_template": {
                    "call_template_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"}

3. Full examples

You can find full examples in the examples repository.

Protocol Specification

UtcpManual and Tool Models

The tool_provider object inside a Tool has been replaced by tool_call_template.

{
  "manual_version": "string",
  "utcp_version": "string",
  "tools": [
    {
      "name": "string",
      "description": "string",
      "inputs": { ... },
      "outputs": { ... },
      "tags": ["string"],
      "tool_call_template": {
        "call_template_type": "http",
        "url": "https://...",
        "http_method": "GET"
      }
    }
  ]
}

Call Template Configuration Examples

Configuration examples for each protocol. Remember to replace provider_type with call_template_type.

HTTP Call Template

{
  "name": "my_rest_api",
  "call_template_type": "http", // Required
  "url": "https://api.example.com/users/{user_id}", // Required
  "http_method": "POST", // Required, default: "GET"
  "content_type": "application/json", // Optional, default: "application/json"
  "allowed_communication_protocols": ["http"], // Optional, defaults to [call_template_type]. Restricts which protocols tools can use.
  "auth": { // Optional, authentication for the HTTP request (example using ApiKeyAuth for Bearer token)
    "auth_type": "api_key",
    "api_key": "Bearer $API_KEY", // Required
    "var_name": "Authorization", // Optional, default: "X-Api-Key"
    "location": "header" // Optional, default: "header"
  },
  "auth_tools": { // Optional, authentication for converted tools, if this call template points to an openapi spec that should be automatically converted to a utcp manual (applied only to endpoints requiring auth per OpenAPI spec)
    "auth_type": "api_key",
    "api_key": "Bearer $TOOL_API_KEY", // Required
    "var_name": "Authorization", // Optional, default: "X-Api-Key"
    "location": "header" // Optional, default: "header"
  },
  "headers": { // Optional
    "X-Custom-Header": "value"
  },
  "body_field": "body", // Optional, default: "body"
  "header_fields": ["user_id"] // Optional
}

SSE (Server-Sent Events) Call Template

{
  "name": "my_sse_stream",
  "call_template_type": "sse", // Required
  "url": "https://api.example.com/events", // Required
  "event_type": "message", // Optional
  "reconnect": true, // Optional, default: true
  "retry_timeout": 30000, // Optional, default: 30000 (ms)
  "auth": { // Optional, example using BasicAuth
    "auth_type": "basic",
    "username": "${USERNAME}", // Required
    "password": "${PASSWORD}" // Required
  },
  "headers": { // Optional
    "X-Client-ID": "12345"
  },
  "body_field": null, // O

…

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [universal-tool-calling-protocol](https://github.com/universal-tool-calling-protocol)
- **Source:** [universal-tool-calling-protocol/python-utcp](https://github.com/universal-tool-calling-protocol/python-utcp)
- **License:** MPL-2.0
- **Homepage:** https://www.utcp.io/

Install and usage instructions live in the source repository linked above.