# Call a tool in a AgentCore gateway To call a specific tool, make a POST request to the gateway’s MCP endpoint. Specify `tools/call` as the method in the request body, along with the name of the tool and its arguments. The request format depends on the MCP protocol version: **Example** ``` POST /mcp HTTP/1.1 Host: ${GatewayEndpoint} Accept: application/json, text/event-stream Content-Type: application/json Authorization: ${Authorization header} MCP-Protocol-Version: ${McpProtocolVersion} ${RequestBody} ``` On version `2026-07-28`, each request carries the `MCP-Protocol-Version` header, the `Mcp-Method` and `Mcp-Name` request-metadata headers, and the `_meta` version fields in the body. ``` POST /mcp HTTP/1.1 Host: ${GatewayEndpoint} Accept: application/json, text/event-stream Content-Type: application/json Authorization: ${Authorization header} MCP-Protocol-Version: 2026-07-28 Mcp-Method: tools/call Mcp-Name: ${ToolName} ${RequestBody} ``` **Note** The gateway accepts only the MCP protocol versions listed in the `supportedVersions` field of its `protocolConfiguration.mcp` configuration. To use version `2026-07-28`, make sure that your gateway’s `supportedVersions` includes it. You can change the supported versions with the [UpdateGateway](https://docs.aws.amazon.com/bedrock-agentcore-control/latest/APIReference/API_UpdateGateway.html) API. Replace the following values: + `${GatewayEndpoint}` – The URL of the gateway, as provided in the response of the [CreateGateway](https://docs.aws.amazon.com/bedrock-agentcore-control/latest/APIReference/API_CreateGateway.html) API. + `${Authorization header}` – The authorization credentials from the identity provider when you set up [inbound authorization](gateway-inbound-auth.md). + `${McpProtocolVersion}` – The MCP protocol version for the request, such as `2025-11-25`. The version must be one that your gateway supports. + `${RequestBody}` – The JSON payload of the request body, as specified in [Calling tools](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#calling-tools) in the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/docs/getting-started/intro) . Include `tools/call` as the `method` and include the `name` of the tool and its `arguments`. The response returns the content returned by the tool and associated metadata. ## Code samples for calling tools To see examples of calling tools in the gateway, select one of the following methods: **Example** The following curl request shows an example request to call a tool called `searchProducts` through a gateway with the ID `mygateway-abcdefghij`. Set the `MCP-Protocol-Version` header to a version that your gateway supports. ``` curl -X POST \ https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp \ -H "Accept: application/json, text/event-stream" \ -H "Content-Type: application/json" \ -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \ -H "MCP-Protocol-Version: 2025-11-25" \ -d '{ "jsonrpc": "2.0", "id": "invoke-tool-request", "method": "tools/call", "params": { "name": "searchProducts", "arguments": { "query": "wireless headphones", "category": "Electronics", "maxResults": 2, "priceRange": { "min": 50.00, "max": 200.00 } } } }' ``` On version `2026-07-28`, include the `Mcp-Method` and `Mcp-Name` request-metadata headers and the `_meta` version fields in the body. The `MCP-Protocol-Version` header must match `_meta.io.modelcontextprotocol/protocolVersion`. Your gateway’s `supportedVersions` must include `2026-07-28`. ``` curl -X POST \ https://mygateway-abcdefghij.gateway.bedrock-agentcore.us-west-2.amazonaws.com/mcp \ -H "Accept: application/json, text/event-stream" \ -H "Content-Type: application/json" \ -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \ -H "MCP-Protocol-Version: 2026-07-28" \ -H "Mcp-Method: tools/call" \ -H "Mcp-Name: searchProducts" \ -d '{ "jsonrpc": "2.0", "id": "invoke-tool-request", "method": "tools/call", "params": { "name": "searchProducts", "arguments": { "query": "wireless headphones", "category": "Electronics", "maxResults": 2, "priceRange": { "min": 50.00, "max": 200.00 } }, "_meta": { "io.modelcontextprotocol/protocolVersion": "2026-07-28", "io.modelcontextprotocol/clientInfo": { "name": "my-agent", "version": "1.0.0" }, "io.modelcontextprotocol/clientCapabilities": {} } } }' ``` Set the `MCP-Protocol-Version` header to a version that your gateway supports. ``` import requests import json def call_tool(gateway_url, access_token, tool_name, arguments): headers = { "Accept": "application/json, text/event-stream", "Content-Type": "application/json", "Authorization": f"Bearer {access_token}", "MCP-Protocol-Version": "2025-11-25" } payload = { "jsonrpc": "2.0", "id": "call-tool-request", "method": "tools/call", "params": { "name": tool_name, "arguments": arguments } } response = requests.post(gateway_url, headers=headers, json=payload) return response.json() # Example usage gateway_url = "https://${GatewayEndpoint}/mcp" # Replace with your actual gateway endpoint access_token = "${AccessToken}" # Replace with your actual access token result = call_tool( gateway_url, access_token, "openapi-target-1___get_orders_byId", # Replace with <{TargetId}__{ToolName}> {"orderId": "ORD-12345-67890", "customerId": "CUST-98765"} ) print(json.dumps(result, indent=2)) ``` On version `2026-07-28`, include the `Mcp-Method` and `Mcp-Name` request-metadata headers and the `_meta` version fields in the body. The `MCP-Protocol-Version` header must match `_meta.io.modelcontextprotocol/protocolVersion`. Your gateway’s `supportedVersions` must include `2026-07-28`. ``` import requests import json def call_tool(gateway_url, access_token, tool_name, arguments): headers = { "Accept": "application/json, text/event-stream", "Content-Type": "application/json", "Authorization": f"Bearer {access_token}", "MCP-Protocol-Version": "2026-07-28", "Mcp-Method": "tools/call", "Mcp-Name": tool_name } payload = { "jsonrpc": "2.0", "id": "call-tool-request", "method": "tools/call", "params": { "name": tool_name, "arguments": arguments, "_meta": { "io.modelcontextprotocol/protocolVersion": "2026-07-28", "io.modelcontextprotocol/clientInfo": {"name": "my-agent", "version": "1.0.0"}, "io.modelcontextprotocol/clientCapabilities": {} } } } response = requests.post(gateway_url, headers=headers, json=payload) return response.json() # Example usage gateway_url = "https://${GatewayEndpoint}/mcp" # Replace with your actual gateway endpoint access_token = "${AccessToken}" # Replace with your actual access token result = call_tool( gateway_url, access_token, "openapi-target-1___get_orders_byId", # Replace with <{TargetId}__{ToolName}> {"orderId": "ORD-12345-67890", "customerId": "CUST-98765"} ) print(json.dumps(result, indent=2)) ``` ``` from mcp import ClientSession from mcp.client.streamable_http import streamablehttp_client import asyncio async def execute_mcp( url, token, tool_params, headers=None ): default_headers = { "Authorization": f"Bearer {token}" } headers = {**default_headers, **(headers or {})} async with streamablehttp_client( url=url, headers=headers, ) as ( read_stream, write_stream, callA, ): async with ClientSession(read_stream, write_stream) as session: # 1. Perform initialization handshake print("Initializing MCP...") _init_response = await session.initialize() print(f"MCP Server Initialize successful! - {_init_response}") # 2. Call specific tool print(f"Calling tool: {tool_params['name']}") tool_response = await session.call_tool( name=tool_params['name'], arguments=tool_params['arguments'] ) print(f"Tool response: {tool_response}") return tool_response async def main(): url = "https://${GatewayEndpoint}/mcp" token = "your_bearer_token_here" tool_params = { "name": "LambdaTarget___get_order_tool", "arguments": { "orderId": "order123" } } await execute_mcp( url=url, token=token, tool_params=tool_params ) if __name__ == "__main__": asyncio.run(main()) ``` NOTE: This is for invoking an agent. ``` from strands.tools.mcp.mcp_client import MCPClient from mcp.client.streamable_http import streamablehttp_client def create_streamable_http_transport(mcp_url: str, access_token: str): return streamablehttp_client(mcp_url, headers={"Authorization": f"Bearer {access_token}"}) def run_agent(mcp_url: str, access_token: str): mcp_client = MCPClient(lambda: create_streamable_http_transport(mcp_url, access_token)) with mcp_client: result = mcp_client.call_tool_sync( tool_use_id="tool-123", # A unique ID for the tool call name="openapi-target-1___get_orders", # The name of the tool to invoke arguments={} # A dictionary of arguments for the tool ) print(result) url = {gatewayUrl} token = {AccessToken} run_agent(url, token) ``` NOTE: This is for invoking an agent. ``` import asyncio from langgraph.prebuilt import create_react_agent def execute_agent( user_prompt, model_id, region, tools ): model = ChatBedrock(model_id=model_id, region_name=region) agent = create_react_agent(model, tools) _response = asyncio.run(agent.ainvoke({ "messages": user_prompt })) _response = _response.get('messages', {})[1].content print( f"Invoke Langchain Agents Response" f"Response - \n{_response}\n" ) return _response ``` ## Errors The `tools/call` operation can return the following types of errors: + Errors returned as part of the HTTP status code: **AuthenticationError** The request failed due to invalid authentication credentials. **HTTP Status Code** : 401 **AuthorizationError** The caller does not have permission to invoke the tool. **HTTP Status Code** : 403 **ResourceNotFoundError** The specified tool does not exist. **HTTP Status Code** : 404 **ValidationError** The provided arguments do not conform to the tool’s input schema. **HTTP Status Code** : 400 **ToolExecutionError** An error occurred while executing the tool. **HTTP Status Code** : 500 **InternalServerError** An internal server error occurred. **HTTP Status Code** : 500 + MCP errors. For more information about these types of errors, [Error Handling](https://modelcontextprotocol.io/specification/2024-11-05/server/tools#error-handlinghttps://modelcontextprotocol.io/specification/2024-11-05/server/tools#error-handling) in the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/docs/getting-started/intro) documentation.