models: Add support for DeepSeek models

[veeragoni]

Features

• New DeepSeek Model Provider: Full implementation with streaming and tool use support
• OpenAI-compatible API: Uses OpenAI client for seamless integration with DeepSeek endpoints
• Tool Use Support: Proper tool calling with calculator, file operations, and shell commands
• Reasoning Model Support: Handles DeepSeek-specific features like reasoning content
• Beta Features: Support for beta endpoint and advanced DeepSeek capabilities

Changes

• src/strands/models/deepseek.py: New DeepSeek model provider implementation with proper tool use streaming
• src/strands/models/__init__.py: Export DeepSeekModel class
• tests_integ/models/test_model_deepseek.py: Comprehensive integration tests (8 test cases)
• tests_integ/models/ds_test.py: Demonstration script showing tool use capabilities
• README.md: Update documentation with DeepSeek examples and provider list

Usage

from strands.models.deepseek import DeepSeekModel
from strands_tools import calculator

model = DeepSeekModel(api_key="your-key", model_id="deepseek-chat")
agent = Agent(model=model, tools=[calculator])
result = agent("What is 42 ^ 9")  # Uses calculator tool correctly

Testing

✅ All 8 integration tests passing
✅ Basic conversation, structured output, streaming, tool usage
✅ Multi-tool workflows (calculator, file_read, shell)
✅ Configuration updates and async operations
✅ Tool use streaming matches OpenAI/Ollama implementations
✅ All mypy type checks passing

Documentation PR

strands-agents/docs#135

Type of Change

New feature

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

I ran hatch run prepare

Checklist

[x] I have read the CONTRIBUTING document
[x] I have added any necessary tests that prove my fix is effective or my feature works
[x] I have updated the documentation accordingly
[x] I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
[x] My changes generate no new warnings
[x] Any dependent changes have been merged and published

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[SamYuan1990]

+1
I am attempting strands agent with official strands agents example and use deep seek as LLM service.
I found some formatting issue, so, if by this PR, we can have official support with DeepSeek instead of OpenAI... that's great.

strands.types.exceptions.EventLoopException: Failed to deserialize the JSON body into the target type: messages[2]: invalid type: sequence, expected a string at line 1 column 755

[mo-silent]

Hi @veeragoni ,
I see the CICD checks are failing. Would you like help fixing these issues?
I'm also interested in adding DeepSeek support and could collaborate with you.

[pgrayy]

Deepseek provides an OpenAI compatible endpoint (docs) and so can already be accessed using Strand's OpenAIModel provider. You just need to pass in the base_url into client_args (docs).

[mo-silent]

Deepseek provides an OpenAI compatible endpoint (docs) and so can already be accessed using Strand's OpenAIModel provider. You just need to pass in the base_url into client_args (docs).

@pgrayy
I think you haven't tried to call Deepseek using the OpenAIModel provider. Deepseek does offer endpoints compatible with OpenAI. But in the OpenAIModel definition of stands-agent, it encapsulates request, which makes it incompatible with deepseek. For specific differences, you can refer to my screenshot:

Processing of agent OpenAIModel

Openai chat create api reference

Deepseek chat create api reference

Solution

1. Add Deepseek module provider
2. Create a Custom Model Provider, inherit from OpenAIModel Provider and add subclasses to handle the content method

However, I have found that many people have the need to call deepseek, so I think it would be better to add a deepseek provider