fix: Moved tool_spec retrieval to after the before model invocation callback (strands-agents#786)

pghazanfari · Parham Ghazanfari · Unshure · commit b10d9f36aa9e · 2025-09-24T15:37:13.000-04:00
Co-authored-by: Parham Ghazanfari &lt;parhamghazanfari@gmail.com&gt;
diff --git a/src/strands/event_loop/event_loop.py b/src/strands/event_loop/event_loop.py
@@ -132,14 +132,14 @@ async def event_loop_cycle(agent: "Agent", invocation_state: dict[str, Any]) ->
             model_id=model_id,
         )
         with trace_api.use_span(model_invoke_span):
-            tool_specs = agent.tool_registry.get_all_tool_specs()
-
             agent.hooks.invoke_callbacks(
                 BeforeModelInvocationEvent(
                     agent=agent,
                 )
             )
 
+            tool_specs = agent.tool_registry.get_all_tool_specs()
+
             try:
                 async for event in stream_messages(agent.model, agent.system_prompt, agent.messages, tool_specs):
                     if not isinstance(event, ModelStopReason):

Original file line number	Diff line number	Diff line change
`@@ -132,14 +132,14 @@ async def event_loop_cycle(agent: "Agent", invocation_state: dict[str, Any]) ->`
`132`	`132`	`model_id=model_id,`
`133`	`133`	`)`
`134`	`134`	`with trace_api.use_span(model_invoke_span):`
`135`		`- tool_specs = agent.tool_registry.get_all_tool_specs()`
`136`		`-`
`137`	`135`	`agent.hooks.invoke_callbacks(`
`138`	`136`	`BeforeModelInvocationEvent(`
`139`	`137`	`agent=agent,`
`140`	`138`	`)`
`141`	`139`	`)`
`142`	`140`
	`141`	`+ tool_specs = agent.tool_registry.get_all_tool_specs()`
	`142`	`+`
`143`	`143`	`try:`
`144`	`144`	`async for event in stream_messages(agent.model, agent.system_prompt, agent.messages, tool_specs):`
`145`	`145`	`if not isinstance(event, ModelStopReason):`