Document streamed tool call arguments

This commit is contained in:
lorenzejay
2026-07-02 11:33:26 -07:00
parent 559a9c65c4
commit b6a4af584d
11 changed files with 667 additions and 16 deletions

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@@ -61,6 +61,35 @@ Frames are grouped into high-level channels:
The stream itself remains one ordered timeline. Channel projections let consumers focus on only part of that timeline.
### Tool Call Streaming
Tool calls appear in two places because there are two distinct phases:
| Phase | Channel | Event type | Meaning |
|-------|---------|------------|---------|
| Tool-call construction | `llm` | `llm_stream_chunk` | The model is streaming the tool name or arguments it intends to call |
| Tool execution | `tools` | `tool_usage_started`, `tool_usage_finished`, `tool_usage_error` | CrewAI is executing the tool and reporting the result |
For streamed tool-call arguments, the latest provider delta is available as `frame.data["chunk"]`. The accumulated argument string is available at `frame.data["tool_call"]["function"]["arguments"]`.
```python
with llm.stream_events("Check the weather in Paris.", tools=[weather_tool]) as stream:
for frame in stream.llm:
if frame.type != "llm_stream_chunk":
continue
tool_call = frame.data.get("tool_call")
if tool_call:
function = tool_call["function"]
print("Tool:", function["name"])
print("Latest argument delta:", frame.data["chunk"])
print("Arguments so far:", function["arguments"])
elif frame.content:
print(frame.content, end="", flush=True)
```
Use the `tools` channel when you want to display that a tool actually started, completed, or failed. Use the `llm` channel when you want to observe the model constructing the tool call before execution.
```mermaid
flowchart LR
A["flow<br/>flow_started"] --> B["llm<br/>llm_call_started"]

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@@ -70,6 +70,38 @@ result = stream.result
`frame.event` is the structured payload for the source event. Use it for metadata such as tool names, arguments, message roles, and runtime identifiers.
## Print Streamed Tool Call Arguments
When a model supports streamed tool calling, CrewAI emits partial tool-call arguments as `llm_stream_chunk` frames on the `llm` channel. These frames are different from tool execution events:
- `llm` channel: the model is constructing the tool call.
- `tools` channel: CrewAI is executing the tool.
The current delta is stored in `frame.event["chunk"]`. The accumulated arguments are stored in `frame.event["tool_call"]["function"]["arguments"]`.
```python
with llm.stream_events("Get the weather in Paris.", tools=[weather_tool]) as stream:
for frame in stream.interleave(["llm", "tools"]):
if frame.channel == "llm" and frame.type == "llm_stream_chunk":
tool_call = frame.event.get("tool_call")
if tool_call:
function = tool_call["function"]
print(f"\nPreparing tool: {function['name']}")
print(f"Arguments so far: {function['arguments']}")
elif frame.content:
print(frame.content, end="", flush=True)
elif frame.channel == "tools" and frame.type == "tool_usage_started":
print(f"\nRunning tool: {frame.event.get('tool_name')}")
elif frame.channel == "tools" and frame.type == "tool_usage_finished":
print(f"\nTool finished: {frame.event.get('tool_name')}")
result = stream.result
```
Some providers emit arguments in small JSON fragments. For display, prefer the accumulated argument string over the latest delta.
## Watch Flow Progress
Flow lifecycle and method execution frames arrive on the `flow` channel:

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@@ -240,15 +240,18 @@ for chunk in streaming:
### TOOL_CALL Chunks
Information about tool calls being made:
Information about tool calls being made. Depending on the provider, CrewAI may receive tool-call arguments incrementally. In that case, each `TOOL_CALL` chunk contains the latest streamed content in `chunk.content`, while `chunk.tool_call.arguments` contains the accumulated argument string so far.
```python Code
for chunk in streaming:
if chunk.chunk_type == StreamChunkType.TOOL_CALL:
print(f"\nCalling tool: {chunk.tool_call.tool_name}")
print(f"Arguments: {chunk.tool_call.arguments}")
print(f"Latest argument delta: {chunk.content}")
print(f"Arguments so far: {chunk.tool_call.arguments}")
```
Actual tool execution is reported separately through tool usage events in the runtime event stream and through CrewAI's verbose console output. `TOOL_CALL` chunks represent the model constructing the tool request before or during execution.
## Practical Example: Building a UI with Streaming
Here's a complete example showing how to build an interactive application with streaming:
@@ -381,4 +384,4 @@ except Exception as e:
print("Streaming completed but an error occurred")
```
By leveraging streaming, you can build more responsive and interactive applications with CrewAI, providing users with real-time visibility into agent execution and results.
By leveraging streaming, you can build more responsive and interactive applications with CrewAI, providing users with real-time visibility into agent execution and results.

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@@ -145,6 +145,33 @@ result = stream.result
`llm.stream_events(...)` temporarily enables streaming for the wrapped call and restores the LLM's previous `stream` setting afterward. Provider integrations continue to emit the underlying LLM stream events; this helper provides a common iterator API over those events for every LLM provider.
### Tool Call Argument Deltas
Native tool-call streaming uses `llm_stream_chunk` frames on the `llm` channel. This represents the model constructing a tool call. It is separate from the `tools` channel, which represents CrewAI executing that tool.
For a streamed tool call, the frame payload includes:
```python
frame.type == "llm_stream_chunk"
frame.channel == "llm"
frame.event["call_type"] == "tool_call"
frame.event["chunk"] # latest argument delta from the provider
frame.event["tool_call"] # accumulated tool-call state
```
The `tool_call` payload follows the OpenAI-style function call shape:
```python
tool_call = frame.event["tool_call"]
tool_call["id"]
tool_call["index"]
tool_call["type"] # "function"
tool_call["function"]["name"]
tool_call["function"]["arguments"] # accumulated JSON argument string
```
Providers differ in granularity. OpenAI and Anthropic may stream arguments as small JSON fragments, while some providers emit the complete argument object in one chunk. Consumers should treat `frame.event["chunk"]` as the latest delta and `tool_call["function"]["arguments"]` as the current accumulated state.
## Conversational Turns
Conversational Flows can stream one user turn with `stream_turn()`: