bug: DeepSeek agent fails to execute tools properly

[nanlong]

• I have looked for existing issues (including closed) about this

Bug Report

The DeepSeek agent fails to properly execute tools when running the calculator example. While the basic text generation works, the agent does not correctly handle tool calls for arithmetic operations.

Reproduction

1. Run the calculator example:

cargo run --example agent_with_deepseek

2. The example code:

let calculator_agent = client
    .agent(providers::deepseek::DEEPSEEK_CHAT)
    .preamble("You are a calculator here to help the user perform arithmetic operations. Use the tools provided to answer the user's question.")
    .max_tokens(1024)
    .tool(Adder)
    .tool(Subtract)
    .build();

println!("Calculate 2 - 5");
println!(
    "DeepSeek Calculator Agent: {}",
    calculator_agent.prompt("Calculate 2 - 5").await?
);

Expected behavior

• The agent should recognize the arithmetic operation #request
• Use the appropriate tool (Subtract in this case)
• Return the calculated result (-3)

Actual behavior

The agent fails to properly execute the tool calls, either:

• Not recognizing the need to use tools
• Or failing to properly format tool calls
• Or not handling tool responses correctly

Environment

• Rust version: (1.84.1)
• OS: (macOs Sonoma 14.5)
• Rig version: (0.8.0)

Additional context

This appears to be specific to the DeepSeek provider implementation, as similar tool usage works with other providers. The issue impacts the core functionality of using tools with DeepSeek agents.

[0xMochan]

Hey, thanks for this issue! PR #283 just got merged, does this solve this issue?

[nanlong]

Yes, there are no more questions. Thank you for your work!