diff --git a/docs/evaluate/index.md b/docs/evaluate/index.md
index f676ce2b8..8fe34cce2 100644
--- a/docs/evaluate/index.md
+++ b/docs/evaluate/index.md
@@ -382,6 +382,14 @@ generated by an AI model.
 For details on how to set up an eval with user simulation, see
 [User Simulation](./user-sim.md).
 
+### Tool Simulation / Agent Simulator
+When evaluating agents, it is often useful to simulate tool outputs rather than calling real APIs. This allows for:
+- Deterministic testing
+- Fault injection (errors, latency)
+- Cost savings
+
+The [Agent Simulator](./agent-simulator.md) provides a flexible way to mock tools and inject behaviors.
+
 ## How to run Evaluation with the ADK
 
 As a developer, you can evaluate your agents using the ADK in the following ways:
@@ -507,4 +515,4 @@ Here are the details for each command line argument:
 * For example: `sample_eval_set_file.json:eval_1,eval_2,eval_3`  
   `This will only run eval_1, eval_2 and eval_3 from sample_eval_set_file.json`  
 * `CONFIG_FILE_PATH`: The path to the config file.  
-* `PRINT_DETAILED_RESULTS`: Prints detailed results on the console.
+* `PRINT_DETAILED_RESULTS`: Prints detailed results on the console.
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