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. 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.

UTCP has been refactored into a core library and a set of optional plugins.

The utcp package provides the central components and interfaces:

• Data Models: Pydantic models for Tool, CallTemplate, UtcpManual, and Auth.
• Pluggable Interfaces:
  • CommunicationProtocol: Defines the contract for protocol-specific communication (e.g., HTTP, CLI).
  • ConcurrentToolRepository: An interface for storing and retrieving tools with thread-safe access.
  • ToolSearchStrategy: An interface for implementing tool search algorithms.
  • VariableSubstitutor: Handles variable substitution in configurations.
  • ToolPostProcessor: Allows for modifying tool results before they are returned.
• Default Implementations:
  • UtcpClient: The main client for interacting with the UTCP ecosystem.
  • InMemToolRepository: An in-memory tool repository with asynchronous read-write locks.
  • TagAndDescriptionWordMatchStrategy: An improved search strategy that matches on tags and description keywords.

Communication protocols are now separate, installable packages. This keeps the core lean and allows users to install only the protocols they need.

• utcp-http: Supports HTTP, SSE, and streamable HTTP, plus an OpenAPI converter.
• utcp-cli: For wrapping local command-line tools.
• utcp-mcp: For interoperability with the Model Context Protocol (MCP).
• utcp-text: For reading text files.
• utcp-socket: Scaffolding for TCP and UDP protocols. (Work in progress, requires update)
• utcp-gql: Scaffolding for GraphQL. (Work in progress, requires update)

Install the core library and any required protocol plugins.

# Install the core client and the HTTP plugin
pip install utcp utcp-http

# Install the CLI plugin as well
pip install utcp-cli

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

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.
3. 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.
4. 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.
5. Tool Naming: Tool names are now namespaced as manual_name.tool_name. The client handles this automatically.
6. 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.

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())

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": "1.0.1",
        "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"}

You can find full examples in the examples repository.

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"
      }
    }
  ]
}

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

{
  "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"
  "auth": { // Optional, example using ApiKeyAuth for a Bearer token. The client must prepend "Bearer " to the token.
    "auth_type": "api_key",
    "api_key": "Bearer $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
}

{
  "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, // Optional
  "header_fields": [] // Optional
}

Note the name change from http_stream to streamable_http.

{
  "name": "streaming_data_source",
  "call_template_type": "streamable_http", // Required
  "url": "https://api.example.com/stream", // Required
  "http_method": "POST", // Optional, default: "GET"
  "content_type": "application/octet-stream", // Optional, default: "application/octet-stream"
  "chunk_size": 4096, // Optional, default: 4096
  "timeout": 60000, // Optional, default: 60000 (ms)
  "auth": null, // Optional
  "headers": {}, // Optional
  "body_field": "data", // Optional
  "header_fields": [] // Optional
}

{
  "name": "my_cli_tool",
  "call_template_type": "cli", // Required
  "command_name": "my-command --utcp", // Required
  "env_vars": { // Optional
    "MY_VAR": "my_value"
  },
  "working_dir": "/path/to/working/directory", // Optional
  "auth": null // Optional (always null for CLI)
}

{
  "name": "my_text_manual",
  "call_template_type": "text", // Required
  "file_path": "./manuals/my_manual.json", // Required
  "auth": null // Optional (always null for Text)
}

{
  "name": "my_mcp_server",
  "call_template_type": "mcp", // Required
  "config": { // Required
    "mcpServers": {
      "server_name": {
        "transport": "stdio",
        "command": ["python", "-m", "my_mcp_server"]
      }
    }
  },
  "auth": { // Optional, example using OAuth2
    "auth_type": "oauth2",
    "token_url": "https://auth.example.com/token", // Required
    "client_id": "${CLIENT_ID}", // Required
    "client_secret": "${CLIENT_SECRET}", // Required
    "scope": "read:tools" // Optional
  }
}

The testing structure has been updated to reflect the new core/plugin split.

To run all tests for the core library and all plugins:

# Ensure you have installed all dev dependencies
python -m pytest

To run tests for a specific package (e.g., the core library):

python -m pytest core/tests/

To run tests for a specific plugin (e.g., HTTP):

python -m pytest plugins/communication_protocols/http/tests/ -v

To run tests with coverage:

python -m pytest --cov=utcp --cov-report=xml

The build process now involves building each package (core and plugins) separately if needed, though they are published to PyPI independently.

1. Create and activate a virtual environment.
2. Install build dependencies: pip install build.
3. Navigate to the package directory (e.g., cd core).
4. Run the build: python -m build.
5. The distributable files (.whl and .tar.gz) will be in the dist/ directory.