# Parallel Tool Calls

> Allow the model to emit several independent tool calls in one assistant turn; the host executes them in parallel.

- **Category**: Agentic AI
- **Subcategory**: Routing & Composition
- **Canonical URL**: https://designpattern.fyi/patterns/parallel_tool_calls/

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## Description
**Intent**: Allow the model to emit several independent tool calls in one assistant turn; the host executes them in parallel.
**Context**: A tool-using agent is on a task where the next step naturally splits into several independent lookups or actions — fetch three records from different tables, read four files, query two APIs that have nothing to do with each other. The provider's chat API supports a single assistant turn that contains more than one tool call, and the model is capable of identifying these independent calls in one breath rather than thinking step by step.
**Solution**: The provider's API allows the assistant turn to contain multiple tool calls. The host fans them out concurrently (with bounded concurrency and rate-limit handling). Results return as multiple tool messages; the next assistant turn sees all of them.


## Use Cases
- The model frequently issues multiple independent tool calls per turn.
- The provider's API supports multiple tool calls in one assistant message.
- The host can fan out concurrent calls with bounded concurrency and rate-limit handling.





## Trade-offs


### Advantages

- Lower wall-clock latency on parallelisable steps.

- Simpler than full DAG planning.




### Considerations & Drawbacks

- Provider-specific behaviour.

- Host concurrency control complexity.

- Silent correctness bugs when accidentally-dependent calls are parallelised.







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**Reference**: [Original Source](https://www.agentpatternscatalog.org/patterns/parallel-tool-calls/)