Moatless Tools is a hobby project where I experiment with some ideas I have about how LLMs can be used to edit code in large existing codebases. I believe that rather than relying on an agent to reason its way to a solution, it is crucial to build good tools to insert the right context into the prompt and handle the response.

For the implementation used in the paper SWE-Search: Enhancing Software Agents with Monte Carlo Tree Search and Iterative Refinement, please see moatless-tree-search.

SWE-Bench

I use the SWE-bench benchmark as a way to verify my ideas.

• Claude 4 Sonnet - 70.8% solve rate, $0.63 per instance.

Try it out

Run in Docker

1. Clone the repository:

   git clone https://github.com/aorwall/moatless-tools.git
   cd moatless-tools
   

2. Set up environment variables:

   cp .env.example .env
   

   Edit the .env file to set your API keys and other configuration options, including the required MOATLESS_DIR variable:

   MOATLESS_DIR=/path/to/your/moatless/data
   

   Note: MOATLESS_DIR specifies the directory where Moatless will store configuration files and trajectory data. This directory will be mounted as a volume in the Docker containers.

3. Start the services:

   make run
   

4. Access the UI at http://localhost

Install from PyPI

# Install base package only
pip install moatless

# Install with Kubernetes runner support
pip install "moatless[kubernetes]"

Install from source

Clone the repository and install using Poetry

# Clone the repository
git clone https://github.com/aorwall/moatless-tools.git
cd moatless-tools

# Install using uv
uv sync

Code Examples

Basic agent flow

from moatless.actions import Respond
from moatless.agent import ActionAgent
from moatless.completion.tool_call import ToolCallCompletionModel

completion_model = ToolCallCompletionModel(
    model="gpt-4.1-mini",
    temperature=0.0,
    model_api_key=""
)

agent = ActionAgent(
    completion_model=completion_model,
    system_prompt="You are a helpful assistant that can answer questions.",
    actions=[
        Respond()
    ]
)

observation = await agent.run_simple("Hello")

print(observation.message)

Code inspector agent

[notebooks/code_inspector_agent.ipynb](See notebook)

Run SWE-Bench evaluations

Before running the evaluation, you'll need:

1. At least one LLM provider API key (e.g., OpenAI, Anthropic, etc.)
2. A Voyage AI API key from voyageai.com to use the pre-embedded vector stores for SWE-Bench instances.

Verify Setup

Before running the full evaluation, you can verify your setup running a simple SWE-Bench instance.

uv run python scripts/docker_run.py  --flow swebench_tools --model-id gpt-4o-mini-2024-07-18 --instance-id django__django-11099 --evaluation-name testing_setup

The script will run the model against a sample SWE-Bench instance

Results are saved in .moatless/projects/testing_setup.

Run evaluation

Evaluation script to run evaluation in a docker containers.

python3 scripts/run_evaluation.py  --model gpt-4o-mini-2024-07-18 --dataset-split [dataset_split] --evaluation-name [evaluation_name]

Required arguments:

• --dataset-split: Dataset split to use
• --evaluation-name: Name of the evaluation

Optional arguments:

• --model: Model to use for evaluation (default: gpt-4o-mini-2024-07-18, equivalent to --model-id)
• --model-id: Model configuration ID to use (replaces entire model configuration)
• --litellm-model-name: LiteLLM model name to override (keeps other model settings)
• --flow: Flow to use for evaluation (defaults to "simple_coding")
• --num-parallel-jobs: Number of parallel jobs (default: 1)

Flows

Available flows that can be specified with the --flow argument:

Flow ID	Format	Best Suited For	Default Model
swebench_tools	Function calling	Models with native function calling support	gpt-4o-mini-2024-07-18
swebench_tools_and_reasoning	Function calling	Reasoning models with native function calling support	claude-sonnet-4-20250514
swebench_react	ReACT	Open source models without native function calling support	openrouter/mistralai/devstral-small
swebench_react_reasoning	ReACT	Reasoning models without function calling support	openrouter/deepseek/deepseek-r1-0528

Model Configuration

Both evaluation scripts support flexible model configuration through the following options:

Model Options

• --model-id: Specify a complete model configuration ID. This replaces the entire completion model configuration including temperature, max tokens, and all other settings.
• --litellm-model-name: Override only the LiteLLM model name while keeping all other completion model settings (temperature, max tokens, etc.) from the flow or model configuration.

Verified Models

Default model configurations are provided for verified models. Note that other models may work but have not been extensively tested. Verified models are models that have been tested and found to work with the Verified Mini subset of the SWE-Bench dataset.

When specifying just the --model-id argument, the following configurations are used:

Model	Response Format	Message History	Thoughts in Action	Verified Mini
claude-3-5-sonnet-20241022	tool_call	messages	no	46%
claude-3-5-haiku-20241022	tool_call	messages	no	28%
gpt-4o-2024-11-20	tool_call	messages	yes	32%
gpt-4o-mini-2024-07-18	tool_call	messages	yes	16%
o1-mini-2024-09-12	react	react	no (disabled thoughts)	28%
deepseek/deepseek-chat	react	react	no	36%
deepseek/deepseek-reasoner	react	react	no (disabled thoughts)	50%
gemini/gemini-2.0-flash-exp	react	react	no	38%
openrouter/meta-llama/llama-3.1-70b-instruct	react	react	no	-
openrouter/meta-llama/llama-3.1-405b-instruct	react	react	no	28%
openrouter/qwen/qwen-2.5-coder-32b-instruct	react	react	no	32%

Dataset splits

Available dataset splits that can be specified with the --dataset-split argument:

Split Name	Description	Instance Count
lite	All instances from the lite dataset	300
verified	All instances from the verified dataset	500
verified_mini	MariusHobbhahn/swe-bench-verified-mini, a subset of SWE-Bench Verified	50
lite_and_verified_solvable	Instances that exist in both lite and verified datasets and have at least one solved submission to SWE-Bench	84

Example usage

# Run evaluation with Claude 3.5 Sonnet using complete model configuration
python3 scripts/run_evaluation.py \
  --model-id claude-3-5-sonnet-20241022 \
  --flow swebench_tools_and_reasoning \
  --dataset-split verified_mini \
  --num-parallel-jobs 5

# Run evaluation overriding just the model name while keeping flow's model settings
python3 scripts/run_evaluation.py \
  --litellm-model-name openrouter/qwen/qwen-2.5-coder-32b-instruct \
  --flow swebench_react \
  --dataset-split verified_mini \
  --num-parallel-jobs 5