AgentHook

This docs was updated at: 2026-03-21

com.paragon.harness.AgentHook  ·  Interface

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Lifecycle hook that intercepts agent and tool execution events.

Implement this interface to inject cross-cutting concerns (logging, rate limiting, cost tracking, circuit breakers, etc.) without modifying agent logic.

Hooks are executed in registration order. All default methods are no-ops, so you only override the lifecycle events you care about.

Example — log every tool call: {@code AgentHook loggingHook = new AgentHook() {

See Also

• HookRegistry

Since: 1.0

Methods

beforeRun

default void beforeRun(@NonNull AgenticContext context)

Called before the agent's agentic loop starts.

Parameters

Name	Description
context	the conversation context at the start of this run

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afterRun

default void afterRun(@NonNull AgentResult result, @NonNull AgenticContext context)

Called after the agent's agentic loop completes (success or failure).

Parameters

Name	Description
result	the result of the run
context	the conversation context at completion

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beforeToolCall

default void beforeToolCall(@NonNull FunctionToolCall call, @NonNull AgenticContext context)

Called before a tool is invoked. Can be used to block or log tool calls.

Parameters

Name	Description
call	the tool call that is about to be executed
context	the current conversation context

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afterToolCall

default void afterToolCall(
      @NonNull FunctionToolCall call,
      @NonNull ToolExecution execution,
      @NonNull AgenticContext context)

Called after a tool has been invoked.

Parameters

Name	Description
call	the tool call that was executed
execution	the execution record containing output and timing
context	the current conversation context