llm/docs/python-api.md

(python-api)=

Python API

LLM provides a Python API for executing prompts, in addition to the command-line interface.

Understanding this API is also important for writing {ref}plugins.

Basic prompt execution

To run a prompt against the gpt-4o-mini model, run this:

import llm

model = llm.get_model("gpt-4o-mini")
# Optional, you can configure the key in other ways:
model.key = "sk-..."
response = model.prompt("Five surprising names for a pet pelican")
print(response.text())

The llm.get_model() function accepts model IDs or aliases. You can also omit it to use the currently configured default model, which is gpt-4o-mini if you have not changed the default.

In this example the key is set by Python code. You can also provide the key using the OPENAI_API_KEY environment variable, or use the llm keys set openai command to store it in a keys.json file, see {ref}api-keys.

The __str__() method of response also returns the text of the response, so you can do this instead:

print(llm.get_model().prompt("Five surprising names for a pet pelican"))

You can run this command to see a list of available models and their aliases:

llm models

If you have set a OPENAI_API_KEY environment variable you can omit the model.key = line.

Calling llm.get_model() with an invalid model ID will raise a llm.UnknownModelError exception.

(python-api-system-prompts)=

System prompts

For models that accept a system prompt, pass it as system="...":

response = model.prompt(
    "Five surprising names for a pet pelican",
    system="Answer like GlaDOS"
)

(python-api-attachments)=

Attachments

Model that accept multi-modal input (images, audio, video etc) can be passed attachments using the attachments= keyword argument. This accepts a list of llm.Attachment() instances.

This example shows two attachments - one from a file path and one from a URL:

import llm

model = llm.get_model("gpt-4o-mini")
response = model.prompt(
    "Describe these images",
    attachments=[
        llm.Attachment(path="pelican.jpg"),
        llm.Attachment(url="https://static.simonwillison.net/static/2024/pelicans.jpg"),
    ]
)

Use llm.Attachment(content=b"binary image content here") to pass binary content directly.

You can check which attachment types (if any) a model supports using the model.attachment_types set:

model = llm.get_model("gpt-4o-mini")
print(model.attachment_types)
# {'image/gif', 'image/png', 'image/jpeg', 'image/webp'}

if "image/jpeg" in model.attachment_types:
    # Use a JPEG attachment here
    ...

(python-api-schemas)=

Schemas

As with {ref}the CLI tool <usage-schemas> some models support passing a JSON schema should be used for the resulting response.

You can pass this to the prompt(schema=) parameter as either a Python dictionary or a Pydantic BaseModel subclass:

import llm, json
from pydantic import BaseModel

class Dog(BaseModel):
    name: str
    age: int

model = llm.get_model("gpt-4o-mini")
response = model.prompt("Describe a nice dog", schema=Dog)
dog = json.loads(response.text())
print(dog)
# {"name":"Buddy","age":3}

You can also pass a schema directly, like this:

response = model.prompt("Describe a nice dog", schema={
    "properties": {
        "name": {"title": "Name", "type": "string"},
        "age": {"title": "Age", "type": "integer"},
    },
    "required": ["name", "age"],
    "title": "Dog",
    "type": "object",
})

You can also use LLM's {ref}alternative schema syntax <schemas-dsl> via the llm.schema_dsl(schema_dsl) function. This provides a quick way to construct a JSON schema for simple cases:

print(model.prompt(
    "Describe a nice dog with a surprising name",
    schema=llm.schema_dsl("name, age int, bio")
))

Pass multi=True to generate a schema that returns multiple items matching that specification:

print(model.prompt(
    "Describe 3 nice dogs with surprising names",
    schema=llm.schema_dsl("name, age int, bio", multi=True)
))

(python-api-model-options)=

Model options

For models that support options (view those with llm models --options) you can pass options as keyword arguments to the .prompt() method:

model = llm.get_model()
print(model.prompt("Names for otters", temperature=0.2))

(python-api-models-api-keys)=

Passing an API key

Models that accept API keys should take an additional key= parameter to their model.prompt() method:

model = llm.get_model("gpt-4o-mini")
print(model.prompt("Names for beavers", key="sk-..."))

If you don't provide this argument LLM will attempt to find it from an environment variable (OPENAI_API_KEY for OpenAI, others for different plugins) or from keys that have been saved using the {ref}llm keys set <api-keys> command.

Some model plugins may not yet have been upgraded to handle the key= parameter, in which case you will need to use one of the other mechanisms.

(python-api-models-from-plugins)=

Models from plugins

Any models you have installed as plugins will also be available through this mechanism, for example to use Anthropic's Claude 3.5 Sonnet model with llm-anthropic:

pip install llm-anthropic

Then in your Python code:

import llm

model = llm.get_model("claude-3.5-sonnet")
# Use this if you have not set the key using 'llm keys set claude':
model.key = 'YOUR_API_KEY_HERE'
response = model.prompt("Five surprising names for a pet pelican")
print(response.text())

Some models do not use API keys at all.

(python-api-underlying-json)=

Accessing the underlying JSON

Most model plugins also make a JSON version of the prompt response available. The structure of this will differ between model plugins, so building against this is likely to result in code that only works with that specific model provider.

You can access this JSON data as a Python dictionary using the response.json() method:

import llm
from pprint import pprint

model = llm.get_model("gpt-4o-mini")
response = model.prompt("3 names for an otter")
json_data = response.json()
pprint(json_data)

Here's that example output from GPT-4o mini:

{'content': 'Sure! Here are three fun names for an otter:\n'
            '\n'
            '1. **Splash**\n'
            '2. **Bubbles**\n'
            '3. **Otto** \n'
            '\n'
            'Feel free to mix and match or use these as inspiration!',
 'created': 1739291215,
 'finish_reason': 'stop',
 'id': 'chatcmpl-AznO31yxgBjZ4zrzBOwJvHEWgdTaf',
 'model': 'gpt-4o-mini-2024-07-18',
 'object': 'chat.completion.chunk',
 'usage': {'completion_tokens': 43,
           'completion_tokens_details': {'accepted_prediction_tokens': 0,
                                         'audio_tokens': 0,
                                         'reasoning_tokens': 0,
                                         'rejected_prediction_tokens': 0},
           'prompt_tokens': 13,
           'prompt_tokens_details': {'audio_tokens': 0, 'cached_tokens': 0},
           'total_tokens': 56}}

(python-api-token-usage)=

Token usage

Many models can return a count of the number of tokens used while executing the prompt.

The response.usage() method provides an abstraction over this:

pprint(response.usage())

Example output:

Usage(input=5,
      output=2,
      details={'candidatesTokensDetails': [{'modality': 'TEXT',
                                            'tokenCount': 2}],
               'promptTokensDetails': [{'modality': 'TEXT', 'tokenCount': 5}]})

The .input and .output properties are integers representing the number of input and output tokens. The .details property may be a dictionary with additional custom values that vary by model.

(python-api-streaming-responses)=

Streaming responses

For models that support it you can stream responses as they are generated, like this:

response = model.prompt("Five diabolical names for a pet goat")
for chunk in response:
    print(chunk, end="")

The response.text() method described earlier does this for you - it runs through the iterator and gathers the results into a string.

If a response has been evaluated, response.text() will continue to return the same string.

(python-api-async)=

Async models

Some plugins provide async versions of their supported models, suitable for use with Python asyncio.

To use an async model, use the llm.get_async_model() function instead of llm.get_model():

import llm
model = llm.get_async_model("gpt-4o")

You can then run a prompt using await model.prompt(...):

response = await model.prompt(
    "Five surprising names for a pet pelican"
)
print(await response.text())

Or use async for chunk in ... to stream the response as it is generated:

async for chunk in model.prompt(
    "Five surprising names for a pet pelican"
):
    print(chunk, end="", flush=True)

This await model.prompt() method takes the same arguments as the synchronous model.prompt() method, for options and attachments and key= and suchlike.

(python-api-conversations)=

Conversations

LLM supports conversations, where you ask follow-up questions of a model as part of an ongoing conversation.

To start a new conversation, use the model.conversation() method:

model = llm.get_model()
conversation = model.conversation()

You can then use the conversation.prompt() method to execute prompts against this conversation:

response = conversation.prompt("Five fun facts about pelicans")
print(response.text())

This works exactly the same as the model.prompt() method, except that the conversation will be maintained across multiple prompts. So if you run this next:

response2 = conversation.prompt("Now do skunks")
print(response2.text())

You will get back five fun facts about skunks.

The conversation.prompt() method supports attachments as well:

response = conversation.prompt(
    "Describe these birds",
    attachments=[
        llm.Attachment(url="https://static.simonwillison.net/static/2024/pelicans.jpg")
    ]
)

Access conversation.responses for a list of all of the responses that have so far been returned during the conversation.

(python-api-listing-models)=

Listing models

The llm.get_models() list returns a list of all available models, including those from plugins.

import llm

for model in llm.get_models():
    print(model.model_id)

Use llm.get_async_models() to list async models:

for model in llm.get_async_models():
    print(model.model_id)

(python-api-response-on-done)=

Running code when a response has completed

For some applications, such as tracking the tokens used by an application, it may be useful to execute code as soon as a response has finished being executed

You can do this using the response.on_done(callback) method, which causes your callback function to be called as soon as the response has finished (all tokens have been returned).

The signature of the method you provide is def callback(response) - it can be optionally an async def method when working with asynchronous models.

Example usage:

import llm

model = llm.get_model("gpt-4o-mini")
response = model.prompt("a poem about a hippo")
response.on_done(lambda response: print(response.usage()))
print(response.text())

Which outputs:

Usage(input=20, output=494, details={})
In a sunlit glade by a bubbling brook,
Lived a hefty hippo, with a curious look.
...

Or using an asyncio model, where you need to await response.on_done(done) to queue up the callback:

import asyncio, llm

async def run():
    model = llm.get_async_model("gpt-4o-mini")
    response = model.prompt("a short poem about a brick")
    async def done(response):
        print(await response.usage())
        print(await response.text())
    await response.on_done(done)
    print(await response.text())

asyncio.run(run())

Other functions

The llm top level package includes some useful utility functions.

set_alias(alias, model_id)

The llm.set_alias() function can be used to define a new alias:

import llm

llm.set_alias("mini", "gpt-4o-mini")

The second argument can be a model identifier or another alias, in which case that alias will be resolved.

If the aliases.json file does not exist or contains invalid JSON it will be created or overwritten.

remove_alias(alias)

Removes the alias with the given name from the aliases.json file.

Raises KeyError if the alias does not exist.

import llm

llm.remove_alias("turbo")

set_default_model(alias)

This sets the default model to the given model ID or alias. Any changes to defaults will be persisted in the LLM configuration folder, and will affect all programs using LLM on the system, including the llm CLI tool.

import llm

llm.set_default_model("claude-3.5-sonnet")

get_default_model()

This returns the currently configured default model, or gpt-4o-mini if no default has been set.

import llm

model_id = llm.get_default_model()

To detect if no default has been set you can use this pattern:

if llm.get_default_model(default=None) is None:
    print("No default has been set")

Here the default= parameter specifies the value that should be returned if there is no configured default.

set_default_embedding_model(alias) and get_default_embedding_model()

These two methods work the same as set_default_model() and get_default_model() but for the default {ref}embedding model <embeddings> instead.