Mistral parallel tool calls default on, disable them for ordered single calls

TL;DR

Use toolchoice any when the task requires at least one tool call, and none when debugging the raw model output without tools. If your Mistral agent fires several tools at once and your tools must run in sequence, set paralleltool_calls to false and handle one tool result per turn.

Steps

1. If your Mistral agent fires several tools at once and your tools must run in sequence, set paralleltoolcalls to false and handle one tool result per turn. Use toolchoice any when the task requires at least one tool call, and none when debugging the raw model output without tools. Log the toolcalls array on every turn during development so parallel calls are visible.

When to use

You are seeing this: Log the tool_calls array on every turn during development so parallel calls are visible. Use this skill when you run into "Mistral parallel tool calls default on, disable them for ordered single calls".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Mistral's official function-calling docs document the parallel tool call control. By default the model can issue multiple tool calls in one response; setting paralleltoolcalls to false forces the model to use single tool calling, at most one tool per response. The docs also show tool_choice modes including auto, none, any, and required for controlling whether and how tools are used.

Verified resolution: If your Mistral agent fires several tools at once and your tools must run in sequence, set paralleltoolcalls to false and handle one tool result per turn. Use toolchoice any when the task requires at least one tool call, and none when debugging the raw model output without tools. Log the toolcalls array on every turn during development so parallel calls are visible.

Source URL: https://github.com/mistralai/platform-docs-public/blob/HEAD/public/studio-api/conversations/function-calling.md