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Register MCP tools

Introduced 3.0

This is an experimental feature and is not recommended for use in a production environment. For updates on the progress of the feature or if you want to leave feedback, join the discussion on the OpenSearch forum.

Use this API to register one or more Model Context Protocol (MCP)-based tools. For more information about supported tools, see Tools.

Endpoints

POST /_plugins/_ml/mcp/tools/_register

Request body fields

The following table lists the available request fields.

Field Data type Required/Optional Description
tools Array Required A list of tools.

The tools array contains a list of tools. Each tool contains the following fields.

Field Data type Required/Optional Description
name String Optional The tool name. The tool name defaults to the type parameter value. If you need to include multiple tools of the same type in the MCP server, specify different names for the tools.
type String Required The tool type. For a list of supported tools, see Tools.
parameters Object Optional The parameters for the tool. The parameters are dependent on the tool type. For information about specific tool types, see Tools.
attributes Object Optional The configuration properties (attributes) for the tool. The most important attribute in this field is the tool’s input_schema, which defines the expected parameter format for the tool. This schema is sent to the large language model (LLM) so it can properly format parameters when executing the tool.

Example request: WebSearchTool

POST /_plugins/_ml/mcp/tools/_register
{
  "tools": [
    {
      "type": "WebSearchTool",
      "name": "GoogleSearchTool",
      "attributes": {
        "input_schema": {
          "type": "object",
          "properties": {
            "engine": {
              "type": "string",
              "description": "The search engine that will be used by the tool."
            },
            "query": {
              "type": "string",
              "description": "The search query parameter that will be used by the engine to perform the search."
            },
            "next_page": {
              "type": "string",
              "description": "The search result's next page link. If this is provided, the WebSearchTool will fetch the next page results using this link and crawl the links on the page."
            }
          },
          "required": [
            "engine",
            "query"
          ]
        },
        "strict": false
      }
    }
  ]
}

Example request: PPLTool

POST /_plugins/_ml/mcp/tools/_register
{
  "type": "PPLTool",
  "name": "TransferQuestionToPPLAndExecuteTool",
  "description": "Use this tool to convert natural language into PPL queries and execute them. Use this tool after you know the index name; otherwise, call IndexRoutingTool first. The input parameters are: {index: IndexName, question: UserQuestion}",
  "parameters": {
    "model_id": "${your_model_id}",
    "model_type": "FINETUNE"
  },
  "attributes": {
    "input_schema": {
      "type": "object",
      "properties": {
        "question": {
          "type": "string",
          "description": "The user's natural language question that needs to be converted to PPL."
        },
        "index": {
          "type": "string",
          "description": "The index on which the generated PPL query will be executed."
        }
      }
    }
  }
}

Example response

OpenSearch responds with the node ID and the status of the creation of all tools for each node:

{
    "_ZNV5BrNTVm6ilcM7Jn1pw": {
        "created": true
    },
    "NZ9aiUCrSp2b5KBqdJGJKw": {
        "created": true
    }
}
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