Tools | Mirascope
MirascopeLilypad

Tools

If you haven't already, we recommend first reading the section on Calls

Tools are user-defined functions that an LLM (Large Language Model) can ask the user to invoke on its behalf. This greatly enhances the capabilities of LLMs by enabling them to perform specific tasks, access external data, interact with other systems, and more.

Mirascope enables defining tools in a provider-agnostic way, which can be used across all supported LLM providers without modification.

Basic Usage and Syntax

There are two ways of defining tools in Mirascope: BaseTool and functions.

You can consider the functional definitions a shorthand form of writing the BaseTool version of the same tool. Under the hood, tools defined as functions will get converted automatically into their corresponding BaseTool.

Let's take a look at a basic example of each:

Mirascope Frog Logo

Mirascope

from mirascope import BaseTool, llm
from pydantic import Field

class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(..., description="The title of the book.")

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor]) 
def identify_author(book: str) -> str:
    return f"Who wrote {book}?"


response = identify_author("The Name of the Wind")
if tool := response.tool: 
    print(tool.call()) 
    # Output: Patrick Rothfuss 
else:
    print(response.content)
Official SDK

In this example we:

  1. Define the GetBookAuthor/get_book_author tool (a dummy method for the example)
  2. Set the tools argument in the call decorator to give the LLM access to the tool.
  3. We call identify_author, which automatically generates the corresponding provider-specific tool schema under the hood.
  4. Check if the response from identify_author contains a tool, which is the BaseTool instance constructed from the underlying tool call
    • If yes, we call the constructed tool's call method and print its output. This calls the tool with the arguments provided by the LLM.
    • If no, we print the content of the response (assuming no tool was called).

The core idea to understand here is that the LLM is asking us to call the tool on its behalf with arguments that it has provided. In the above example, the LLM chooses to call the tool to get the author rather than relying on its world knowledge.

This is particularly important for buildling applications with access to live information and external systems.

For the purposes of this example we are showing just a single tool call. Generally, you would then give the tool call's output back to the LLM and make another call so the LLM can generate a response based on the output of the tool. We cover this in more detail in the section on Agents

Accessing Original Tool Call

The BaseTool instances have a tool_call property for accessing the original LLM tool call.

from mirascope import BaseTool, llm
from pydantic import Field


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(..., description="The title of the book.")

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor])
def identify_author(book: str) -> str:
    return f"Who wrote {book}?"


response = identify_author("The Name of the Wind")
if tool := response.tool:
    print(tool.call())
    # Output: Patrick Rothfuss
    print(f"Original tool call: {tool.tool_call}") 
else:
    print(response.content)

Supported Field Types

While Mirascope provides a consistent interface, type support varies among providers:

TypeOpenAIAnthropicGoogleGroqxAIMistralCohere
str
int
float
bool
bytes-
list
set-
tuple---
dict--
Literal/Enum
BaseModel-
Nested ($def)-

Legend: ✓ (Supported), - (Not Supported)

Consider provider-specific capabilities when working with advanced type structures. Even for supported types, LLM outputs may sometimes be incorrect or of the wrong type. In such cases, prompt engineering or error handling (like retries and reinserting validation errors) may be necessary.

Parallel Tool Calls

In certain cases the LLM will ask to call multiple tools in the same response. Mirascope makes calling all such tools simple:

from mirascope import BaseTool, llm
from pydantic import Field


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(..., description="The title of the book.")

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor])
def identify_authors(books: list[str]) -> str:
    return f"Who wrote {books}?"


response = identify_authors(["The Name of the Wind", "Mistborn: The Final Empire"])
if tools := response.tools:
    for tool in tools:
        print(tool.call())
else:
    print(response.content)

If your tool calls are I/O-bound, it's often worth writing async tools so that you can run all of the tools calls in parallel for better efficiency.

Streaming Tools

Mirascope supports streaming responses with tools, which is useful for long-running tasks or real-time updates:

from mirascope import BaseTool, llm
from pydantic import Field


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(..., description="The title of the book.")

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor], stream=True) 
def identify_authors(books: list[str]) -> str:
    return f"Who wrote {books}?"


stream = identify_authors(["The Name of the Wind", "Mistborn: The Final Empire"])
for chunk, tool in stream: 
    if tool: 
        print(tool.call()) 
    else:
        print(chunk.content, end="", flush=True)
When are tools returned?

When we identify that a tool is being streamed, we will internally reconstruct the tool from the streamed response. This means that the tool won't be returned until the full tool has been streamed and reconstructed on your behalf.

Not all providers support streaming tools

Currently only OpenAI, Anthropic, Mistral, and Groq support streaming tools. All other providers will always return None for tools.

If you think we're missing any, let us know!

Streaming Partial Tools

You can also stream intermediate partial tools and their deltas (rather than just the fully constructed tool) by setting stream={"partial_tools": True}:

from mirascope import BaseTool, llm
from pydantic import Field


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(..., description="The title of the book.")

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(
    provider="openai",
    model="gpt-4o-mini",
    tools=[GetBookAuthor],
    stream={"partial_tools": True}, 
)
def identify_authors(books: list[str]) -> str:
    return f"Who wrote {books}?"


stream = identify_authors(["The Name of the Wind", "Mistborn: The Final Empire"])
for chunk, tool in stream:
    if tool: 
        if tool.delta is not None:  # partial tool
            print(tool.delta)
        else:
            print(tool.call())
    else:
        print(chunk.content, end="", flush=True)

Tool Message Parameters

Calling tools and inserting their outputs into subsequent LLM API calls in a loop in the most basic form of an agent. While we cover this briefly here, we recommend reading the section on Agents for more details and examples.

Generally the next step after the LLM returns a tool call is for you to call the tool on its behalf and supply the output in a subsequent call.

Let's take a look at a basic example of this:

from mirascope import BaseMessageParam, BaseTool, Messages, llm


class GetBookAuthor(BaseTool):
    title: str

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor])
def identify_author(book: str, history: list[BaseMessageParam]) -> Messages.Type:
    messages = [*history] 
    if book:
        messages.append(Messages.User(f"Who wrote {book}?")) 
    return messages


history = []
response = identify_author("The Name of the Wind", history)
history += [response.user_message_param, response.message_param]
while tool := response.tool:
    tools_and_outputs = [(tool, tool.call())]
    history += response.tool_message_params(tools_and_outputs)
    response = identify_author("", history) 
    history.append(response.message_param) 
print(response.content) 
# Output: The Name of the Wind was written by Patrick Rothfuss.

In this example we:

  1. Add history to maintain the messages across multiple calls to the LLM.
  2. Loop until the response no longer has tools calls.
  3. While there are tool calls, call the tools, append their corresponding message parameters to the history, and make a subsequent call with an empty query and updated history. We use an empty query because the original user message is already included in the history.
  4. Print the final response content once the LLM is done calling tools.

Validation and Error Handling

Since BaseTool is a subclass of Pydantic's BaseModel, they are validated on construction, so it's important that you handle potential ValidationError's for building more robust applications:

from typing import Annotated

from mirascope import BaseTool, llm
from pydantic import AfterValidator, Field, ValidationError


def is_upper(v: str) -> str:
    assert v.isupper(), "Must be uppercase"
    return v


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: Annotated[str, AfterValidator(is_upper)] = Field( 
        ..., description="The title of the book."
    )

    def call(self) -> str:
        if self.title == "THE NAME OF THE WIND":
            return "Patrick Rothfuss"
        elif self.title == "MISTBORN: THE FINAL EMPIRE":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor])
def identify_author(book: str) -> str:
    return f"Who wrote {book}?"


response = identify_author("The Name of the Wind")
try: 
    if tool := response.tool:
        print(tool.call())
    else:
        print(response.content)
except ValidationError as e: 
    print(e)
    # > 1 validation error for GetBookAuthor
    #   title
    #     Assertion failed, Must be uppercase [type=assertion_error, input_value='The Name of the Wind', input_type=str]
    #       For further information visit https://errors.pydantic.dev/2.8/v/assertion_error

In this example we've added additional validation, but it's important that you still handle ValidationError's even with standard tools since they are still BaseModel instances and will validate the field types regardless.

Few-Shot Examples

Just like with Response Models, you can add few-shot examples to your tools:

from mirascope import BaseTool, llm
from pydantic import ConfigDict, Field


class GetBookAuthor(BaseTool):
    """Returns the author of the book with the given title."""

    title: str = Field(
        ...,
        description="The title of the book.",
        examples=["The Name of the Wind"], 
    )

    model_config = ConfigDict(
        json_schema_extra={"examples": [{"title": "The Name of the Wind"}]} 
    )

    def call(self) -> str:
        if self.title == "The Name of the Wind":
            return "Patrick Rothfuss"
        elif self.title == "Mistborn: The Final Empire":
            return "Brandon Sanderson"
        else:
            return "Unknown"


@llm.call(provider="openai", model="gpt-4o-mini", tools=[GetBookAuthor])
def identify_author(book: str) -> str:
    return f"Who wrote {book}?"


response = identify_author("The Name of the Wind")
if tool := response.tool:
    print(tool.call())
else:
    print(response.content)

Both approaches will result in the same tool schema with examples included. The function approach gets automatically converted to use Pydantic fields internally, making both methods equivalent in terms of functionality.

ToolKit

The BaseToolKit class enables:

  • Organiziation of a group of tools under a single namespace.
    • This can be useful for making it clear to the LLM when to use certain tools over others. For example, you could namespace a set of tools under "file_system" to indicate that those tools are specifically for interacting with the file system.
  • Dynamic tool definitions.
    • This can be useful for generating tool definitions that are dependent on some input or state. For example, you may want to update the description of tools based on an argument of the call being made.
from mirascope import (
    BaseDynamicConfig,
    BaseToolKit,
    Messages,
    llm,
)
from mirascope.core import toolkit_tool


class BookTools(BaseToolKit): 
    __namespace__ = "book_tools"

    reading_level: str

    @toolkit_tool
    def suggest_author(self, author: str) -> str:
        """Suggests an author for the user to read based on their reading level.

        User reading level: {self.reading_level} # [!code highlight]
        Author you suggest must be appropriate for the user's reading level.
        """
        return f"I would suggest you read some books by {author}"


@llm.call(provider="openai", model="gpt-4o-mini")
def recommend_author(genre: str, reading_level: str) -> BaseDynamicConfig:
    toolkit = BookTools(reading_level=reading_level) 
    return {
        "tools": toolkit.create_tools(), 
        "messages": [Messages.User(f"What {genre} author should I read?")],
    }


response = recommend_author("fantasy", "beginner") 
if tool := response.tool:
    print(tool.call())
    # Output: I would suggest you read some books by J.K. Rowling 

response = recommend_author("fantasy", "advanced") 
if tool := response.tool:
    print(tool.call())
    # Output: I would suggest you read some books by Brandon Sanderson 

In this example we:

  1. Create a BookTools toolkit
  2. We set __namespace__ equal to "book_tools"
  3. We define the reading_level state of the toolkit
  4. We define the suggest_author tool and mark it with @toolkit_tool to identify the method as a tool of the toolkit
  5. We use the {self.reading_level} template variable in the description of the tool.
  6. We create the toolkit with the reading_level argument.
  7. We call create_tools to generate the toolkit's tools. This will generate the tools on every call, ensuring that the description correctly includes the provided reading level.
  8. We call recommend_author with a "beginner" reading level, and the LLM calls the suggest_author tool with its suggested author.
  9. We call recommend_author again but with "advanced" reading level, and again the LLM calls the suggest_author tool with its suggested author.

The core concept to understand here is that the suggest_author tool's description is dynamically generated on each call to recommend_author through the toolkit.

This is why the "beginner" recommendation and "advanced" recommendations call the suggest_author tool with authors befitting the reading level of each call.

Pre-Made Tools and ToolKits

Mirascope provides several pre-made tools and toolkits to help you get started quickly:

Pre-made tools and toolkits require installing the dependencies listed in the "Dependencies" column for each tool/toolkit.

For example:

pip install httpx  # For HTTPX tool
pip install requests  # For Requests tool

Pre-Made Tools

ToolPrimary UseDependenciesKey FeaturesCharacteristics
DuckDuckGoSearchWeb Searchingduckduckgo-search• Multiple query support
• Title/URL/snippet extraction
• Result count control
• Automated formatting
• Privacy-focused search
• Async support (AsyncDuckDuckGoSearch)
• Automatic filtering
• Structured results
HTTPXAdvanced HTTP Requestshttpx• Full HTTP method support (GET/POST/PUT/DELETE)
• Custom header support
• File upload/download
• Form data handling
• Async support (AsyncHTTPX)
• Configurable timeouts
• Comprehensive error handling
• Redirect control
ParseURLContentWeb Content Extractionbeautifulsoup4, httpx• HTML content fetching
• Main content extraction
• Element filtering
• Text normalization
• Automatic cleaning
• Configurable parser
• Timeout settings
• Error handling
RequestsSimple HTTP Requestsrequests• Basic HTTP methods
• Simple API
• Response text retrieval
• Basic authentication
• Minimal configuration
• Intuitive interface
• Basic error handling
• Lightweight implementation

Example using DuckDuckGoSearch:

from mirascope import llm
from mirascope.tools import DuckDuckGoSearch 


@llm.call(provider="openai", model="gpt-4o-mini", tools=[DuckDuckGoSearch]) 
def research(genre: str) -> str:
    return f"Recommend a {genre} book and summarize the story"


response = research("fantasy")
if tool := response.tool:
    print(tool.call())

Pre-Made ToolKits

ToolKitPrimary UseDependenciesTools and FeaturesCharacteristics
FileSystemToolKitFile System OperationsNone• ReadFile: File content reading
• WriteFile: Content writing
• ListDirectory: Directory listing
• CreateDirectory: Directory creation
• DeleteFile: File deletion
• Path traversal protection
• File size limits
• Extension validation
• Robust error handling
• Base directory isolation
DockerOperationToolKitCode & Command Executiondocker, docker engine• ExecutePython: Python code execution with optional package installation
• ExecuteShell: Shell command execution
• Docker container isolation
• Memory limits
• Network control
• Security restrictions
• Resource cleanup

Example using FileSystemToolKit:

from pathlib import Path

from mirascope import BaseDynamicConfig, Messages, llm
from mirascope.tools import FileSystemToolKit 


@llm.call(provider="openai", model="gpt-4o-mini")
def write_blog_post(topic: str, output_file: Path) -> BaseDynamicConfig:
    toolkit = FileSystemToolKit(base_directory=output_file.parent) 
    return {
        "messages": [
            Messages.User(
                content=f"Write a blog post about '{topic}' as a '{output_file.name}'."
            )
        ],
        "tools": toolkit.create_tools(), 
    }


response = write_blog_post("machine learning", Path("introduction.html"))
if tool := response.tool:
    result = tool.call()
    print(result)

Next Steps

Tools can significantly extend LLM capabilities, enabling more interactive and dynamic applications. We encourage you to explore and experiment with tools to enhance your projects and the find the best fit for your specific needs.

Mirascope hopes to provide a simple and clean interface that is both easy to learn and easy to use; however, we understand that LLM tools can be a difficult concept regardless of the supporting tooling.

Next, we recommend learning about how to build Agents that take advantage of these tools.