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API Reference

Complete reference for the osmosis-ai Python SDK.

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Decorators

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@osmosis_reward

Decorator for local reward functions that compute scores without API calls. Signature: 
@osmosis_reward
def function_name(
    solution_str: str,
    ground_truth: str,
    extra_info: dict = None
) -> float
Parameters:
  • solution_str (str, required) - Text to evaluate
  • ground_truth (str, required) - Reference answer
  • extra_info (dict, optional) - Additional context
Returns: float - Score value Example: 
from osmosis_ai import osmosis_reward

@osmosis_reward
def exact_match(solution_str: str, ground_truth: str, extra_info: dict = None) -> float:
    return 1.0 if solution_str.strip() == ground_truth.strip() else 0.0

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@osmosis_rubric

Decorator for LLM-based evaluation functions. Signature: 
@osmosis_rubric
def function_name(
    solution_str: str,
    ground_truth: str | None,
    extra_info: dict
) -> float
Parameters:
  • solution_str (str, required) - Text to evaluate
  • ground_truth (str | None, required) - Reference answer (can be None)
  • extra_info (dict, required) - Configuration and context
Returns: float - Score value Example: 
from osmosis_ai import osmosis_rubric, evaluate_rubric

@osmosis_rubric
def quality_check(solution_str: str, ground_truth: str | None, extra_info: dict) -> float:
    return evaluate_rubric(
        rubric="Evaluate response quality",
        solution_str=solution_str,
        model_info={"provider": "openai", "model": "gpt-5"},
        ground_truth=ground_truth
    )

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Core Functions

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evaluate_rubric()

Evaluate text using an LLM-based rubric. Signature: 
def evaluate_rubric(
    rubric: str,
    solution_str: str,
    model_info: dict,
    ground_truth: str | None = None,
    original_input: str | None = None,
    metadata: dict | None = None,
    score_min: float = 0.0,
    score_max: float = 1.0,
    timeout: int | None = None,
    return_details: bool = False
) -> float | dict
Parameters:
ParameterTypeRequiredDescription
rubricstrYesNatural language evaluation criteria
solution_strstrYesText to evaluate
model_infodictYesLLM provider configuration
ground_truthstrNoReference answer
original_inputstrNoOriginal user query
metadatadictNoAdditional context
score_minfloatNoMinimum score (default: 0.0)
score_maxfloatNoMaximum score (default: 1.0)
timeoutintNoRequest timeout in seconds
return_detailsboolNoReturn full response (default: False)
model_info Structure: 
{
    "provider": "openai",           # Required
    "model": "gpt-5",         # Required
    "api_key": "sk-...",            # Optional
    "api_key_env": "OPENAI_API_KEY", # Optional
    "timeout": 30                   # Optional
}
Returns:
  • float - Score (when return_details=False)
  • dict - Full response with score, explanation, raw payload (when return_details=True)
Example: 
from osmosis_ai import evaluate_rubric

score = evaluate_rubric(
    rubric="Evaluate how helpful the response is.",
    solution_str="Click 'Forgot Password' to reset.",
    model_info={"provider": "openai", "model": "gpt-5"}
)

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Exceptions

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MissingAPIKeyError

Raised when an API key is not found for a provider. 
from osmosis_ai import MissingAPIKeyError

try:
    score = evaluate_rubric(...)
except MissingAPIKeyError as e:
    print(f"API key not found: {e}")

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ProviderRequestError

Raised when a provider request fails. 
from osmosis_ai import ProviderRequestError

try:
    score = evaluate_rubric(...)
except ProviderRequestError as e:
    print(f"Provider error: {e}")

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ModelNotFoundError

Raised when a specified model is not available (subclass of ProviderRequestError). 
from osmosis_ai import ModelNotFoundError

try:
    score = evaluate_rubric(...)
except ModelNotFoundError as e:
    print(f"Model not found: {e}")

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Supported Providers

ProviderIDDefault API Key EnvExample Models
OpenAIopenaiOPENAI_API_KEYgpt-5
AnthropicanthropicANTHROPIC_API_KEYclaude-sonnet-4-5
Google GeminigeminiGOOGLE_API_KEYgemini-2.5-flash
xAIxaiXAI_API_KEYgrok-4
OpenRouteropenrouterOPENROUTER_API_KEY100+ models
CerebrascerebrasCEREBRAS_API_KEYllama3.1-405b

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Type Definitions

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ModelInfo (TypedDict)

from osmosis_ai import ModelInfo

model_info: ModelInfo = {
    "provider": "openai",
    "model": "gpt-5",
    "api_key_env": "OPENAI_API_KEY",
    "timeout": 30
}

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RewardRubricRunResult (TypedDict)

Returned when return_details=True: 
{
    "score": 0.85,              # float
    "explanation": "...",       # str
    "raw_payload": {...}        # dict
}

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Complete Example

from osmosis_ai import osmosis_reward, osmosis_rubric, evaluate_rubric
from dotenv import load_dotenv

load_dotenv()

# Local reward function
@osmosis_reward
def exact_match(solution_str: str, ground_truth: str, extra_info: dict = None) -> float:
    return 1.0 if solution_str.strip() == ground_truth.strip() else 0.0

# Remote rubric evaluator
@osmosis_rubric
def semantic_eval(solution_str: str, ground_truth: str | None, extra_info: dict) -> float:
    return evaluate_rubric(
        rubric="Compare semantic similarity (0-1 scale)",
        solution_str=solution_str,
        ground_truth=ground_truth,
        model_info={"provider": "openai", "model": "gpt-5"}
    )

# Usage
solution = "The capital of France is Paris"
truth = "Paris is France's capital"

local_score = exact_match(solution, truth)
semantic_score = semantic_eval(solution, truth, {})

print(f"Exact match: {local_score}")      # 0.0
print(f"Semantic: {semantic_score}")      # ~1.0

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Next Steps

Quick Start

Learn with examples

Decorators & API Guide

Advanced patterns

CLI Reference

Batch evaluations