Implement load test scripts for MCP server

src/nat/front_ends/mcp/load_test_utils/README.md

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+<!--
+SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+SPDX-License-Identifier: Apache-2.0
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# MCP Server Load Testing
+
+This utility simulates concurrent users making tool calls to MCP servers and generates detailed performance reports for NVIDIA NeMo Agent toolkit.
+
+## Requirements
+
+Before running load tests, ensure you have the following:
+
+- NeMo Agent toolkit with MCP support installed through `nvidia-nat[mcp]`
+- Valid NeMo Agent toolkit workflow configuration with MCP-compatible tools
+
+The `psutil` package is required for monitoring server memory usage during load tests. Install it using the following command:
+
+```bash
+uv pip install psutil
+```
+
+## Quick Start
+
+Run a load test from the project root:
+
+```bash
+python src/nat/front_ends/mcp/load_test_utils/cli.py \
+  --config_file=src/nat/front_ends/mcp/load_test_utils/configs/config.yml
+```
+
+Get help:
+
+```bash
+python src/nat/front_ends/mcp/load_test_utils/cli.py --help
+```
+
+## Configuration
+
+Configure load test options using YAML files stored in the `configs/` directory.
+
+### Example Configuration
+
+```yaml
+# Path to NeMo Agent toolkit workflow configuration file
+config_file: "examples/getting_started/simple_calculator/configs/config.yml"
+
+# Server configuration
+server:
+  host: "localhost"
+  port: 9901
+  transport: "streamable-http"  # Options: "streamable-http" or "sse"
+
+# Load test parameters
+load_test:
+  num_concurrent_users: 10
+  duration_seconds: 30
+  warmup_seconds: 5
+
+# Output configuration
+output:
+  directory: "load_test_results"
+
+# Tool calls to execute during load testing
+tool_calls:
+  - tool_name: "calculator_multiply"
+    args:
+      text: "2 * 3"
+    weight: 2.0  # Called twice as often as weight 1.0 tools
+
+  - tool_name: "calculator_divide"
+    args:
+      text: "10 / 2"
+    weight: 1.0
+```
+
+### Configuration Parameters
+
+#### Required Parameters
+
+**`config_file`** (string)
+: Path to the NeMo Agent toolkit workflow configuration file.
+
+#### Server Configuration
+
+Configure the MCP server settings in the `server` section:
+
+**`host`** (string, default: `"localhost"`)
+: Host address where the MCP server will run.
+
+**`port`** (integer, default: `9901`)
+: Port number for the MCP server.
+
+**`transport`** (string, default: `"streamable-http"`)
+: Transport protocol type. Options: `"streamable-http"` or `"sse"`.
+
+#### Load Test Parameters
+
+Configure load test behavior in the `load_test` section:
+
+**`num_concurrent_users`** (integer, default: `10`)
+: Number of concurrent users to simulate.
+
+**`duration_seconds`** (integer, default: `60`)
+: Duration of the load test in seconds.
+
+**`warmup_seconds`** (integer, default: `5`)
+: Warmup period before measurements begin, in seconds.
+
+#### Output Configuration
+
+Configure report output in the `output` section:
+
+**`directory`** (string, default: `"load_test_results"`)
+: Directory where test reports will be saved.
+
+#### Tool Calls
+
+Define tool calls to execute in the `tool_calls` list. Each tool call includes:
+
+**`tool_name`** (string, required)
+: Name of the MCP tool to call.
+
+**`args`** (dictionary, optional)
+: Arguments to pass to the tool.
+
+**`weight`** (float, default: `1.0`)
+: Relative call frequency. Tools with higher weights are called more frequently. A tool with weight 2.0 is called twice as often as a tool with weight 1.0.
+
+## Running Load Tests
+
+### Command Line
+
+Run load tests from the project root using the command-line interface:
+
+```bash
+# Basic usage
+python src/nat/front_ends/mcp/load_test_utils/cli.py \
+  --config_file=src/nat/front_ends/mcp/load_test_utils/configs/config.yml
+
+# With verbose logging
+python src/nat/front_ends/mcp/load_test_utils/cli.py \
+  --config_file=src/nat/front_ends/mcp/load_test_utils/configs/config.yml \
+  --verbose
+
+# Short form
+python src/nat/front_ends/mcp/load_test_utils/cli.py \
+  -c src/nat/front_ends/mcp/load_test_utils/configs/config.yml
+```
+
+### Python API
+
+#### Using YAML Configuration
+
+```python
+from nat.front_ends.mcp.load_test_utils import run_load_test_from_yaml
+
+results = run_load_test_from_yaml(
+    "src/nat/front_ends/mcp/load_test_utils/configs/config.yml"
+)
+```
+
+#### Programmatic Usage
+
+```python
+from nat.front_ends.mcp.load_test_utils import run_load_test
+
+results = run_load_test(
+    config_file="examples/getting_started/simple_calculator/configs/config.yml",
+    tool_calls=[
+        {
+            "tool_name": "calculator_multiply",
+            "args": {"text": "2 * 3"},
+            "weight": 2.0,
+        },
+        {
+            "tool_name": "calculator_divide",
+            "args": {"text": "10 / 2"},
+            "weight": 1.0,
+        },
+    ],
+    num_concurrent_users=10,
+    duration_seconds=30,
+)
+```
+
+## Output Reports
+
+The load test generates two report files in the output directory:
+
+### CSV Report
+
+**File name**: `load_test_YYYYMMDD_HHMMSS.csv`
+
+Detailed per-request data with the following columns:
+
+- `timestamp`: Request timestamp
+- `tool_name`: Name of the tool called
+- `success`: Boolean success status
+- `latency_ms`: Request latency in milliseconds
+- `memory_rss_mb`: Resident Set Size (RSS) memory in MB at request time
+- `memory_vms_mb`: Virtual Memory Size (VMS) in MB at request time
+- `memory_percent`: Memory usage percentage at request time
+- `error`: Error message if the request failed
+
+### Summary Report
+
+**File name**: `load_test_YYYYMMDD_HHMMSS_summary.txt`
+
+Human-readable summary with the following statistics:
+
+**Summary Metrics**
+: Total requests, success rate, requests per second
+
+**Latency Statistics**
+: Mean, median, P95, P99, minimum, and maximum latencies
+
+**Memory Statistics**
+: RSS and VMS memory usage (mean and max), memory percentage (mean and max)
+
+**Per-Tool Statistics**
+: Individual performance metrics for each tool
+
+**Error Analysis**
+: Breakdown of failed requests by error type

src/nat/front_ends/mcp/load_test_utils/__init__.py

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+# SPDX-FileCopyrightText: Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""MCP Server Load Testing Utilities.
+
+This module provides utilities for load testing MCP servers.
+"""
+
+from nat.front_ends.mcp.load_test_utils.load_tester import MCPLoadTest
+from nat.front_ends.mcp.load_test_utils.load_tester import run_load_test
+from nat.front_ends.mcp.load_test_utils.load_tester import run_load_test_from_yaml
+
+__all__ = ["MCPLoadTest", "run_load_test", "run_load_test_from_yaml"]