Before Execution Modifiers

Before execution modifiers are part of Composio SDK's powerful middleware capabilities that allow you to customize and extend the behavior of tools.

These modifiers are called before the tool is executed by the LLM. This allows you to modify the arguments called by the LLM before they are executed by Composio.

Useful for:

Injecting an argument into the tool execution
Overriding the arguments emitted by the LLM

Below we use the beforeExecute modifier to modify the number of posts returned by HACKERNEWS_GET_LATEST_POSTS.

With Chat Completions

Since completion providers don't have a function execution step, Composio executes the tool call directly. The modifier is configured on the tools.execute method.

from openai import OpenAI
from composio import Composio, before_execute
from composio.types import ToolExecuteParams

composio = Composio()
openai_client = OpenAI()
user_id = "user@email.com"

@before_execute(tools=["HACKERNEWS_GET_LATEST_POSTS"])
def before_execute_modifier(
    tool: str,
    toolkit: str,
    params: ToolExecuteParams,
) -> ToolExecuteParams:
    params["arguments"]["size"] = 1
    return params

# Get tools
tools = composio.tools.get(user_id=user_id, slug="HACKERNEWS_GET_LATEST_POSTS")

# Get response from the LLM
response = openai_client.chat.completions.create(
    model="gpt-4o-mini",
    tools=tools,
    messages=[{"role": "user", "content": "Fetch latest posts from hackernews"}],
)
print(response)

# Execute the function calls
result = composio.provider.handle_tool_calls(
    response=response,
    user_id="default",
    modifiers=[
        before_execute_modifier,
    ],
)
print(result)

const response = await openai.chat.completions.create({
  model: "gpt-4o-mini",
  messages,
  tools,
  tool_choice: "auto",
});

const { tool_calls } = response.choices[0].message;
console.log(tool_calls);

if (tool_calls) {
  const {
    function: { arguments: toolArgs },
  } = tool_calls[0];

  const result = await composio.tools.execute(
    "HACKERNEWS_GET_LATEST_POSTS",
    {
      userId,
      arguments: JSON.parse(toolArgs),
    },
    {
      beforeExecute: ({ toolSlug, toolkitSlug, params }) => {
        if (toolSlug === "HACKERNEWS_GET_LATEST_POSTS") {
          params.arguments.size = 1;
        }
        console.log(params);
        return params;
      },
    }
  );
  console.log(JSON.stringify(result, null, 2));
}

With Agentic Frameworks

Agentic providers have a function execution step. The modifier is configured on the tools.get method which modifies the execution logic within the framework.

from composio import Composio, before_execute
from composio.types import ToolExecuteParams
from composio_crewai import CrewAIProvider

composio = Composio(provider=CrewAIProvider())

@before_execute(tools=["LINEAR_CREATE_LINEAR_ISSUE"])
def modify_linear_project_id(
    tool: str,
    toolkit: str,
    params: ToolExecuteParams,
) -> ToolExecuteParams:
    params["arguments"]["project_id"] = "1234567890"
    return params

tools = composio.tools.get(
    user_id="default",
    tools=[
        "HACKERNEWS_GET_LATEST_POSTS",
        "HACKERNEWS_GET_USER",
        "LINEAR_CREATE_LINEAR_ISSUE",
    ],
    modifiers=[
        modify_linear_project_id,
    ]
)

import { Composio } from "@composio/core";
import { MastraProvider } from "@composio/mastra";

const composio = new Composio({
  apiKey: process.env.COMPOSIO_API_KEY,
  provider: new MastraProvider(),
});

const userId = "user@acme.com";

const agenticTools = await composio.tools.get(
  userId,
  {
    tools: [
      "HACKERNEWS_GET_LATEST_POSTS",
      "HACKERNEWS_GET_USER",
      "LINEAR_CREATE_LINEAR_ISSUE",
    ],
  },
  {
    beforeExecute: ({toolSlug, toolkitSlug, params}) => {
      if (toolSlug === "LINEAR_CREATE_LINEAR_ISSUE") {
        params.arguments.project_id = "1234567890";
      }
      return params;
    },
  }
);

Before Execution Modifiers

With Chat Completions

With Agentic Frameworks

On this page