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# RunContext

> Context object available inside tool handler functions.

[agentsession]: /docs/server-sdks/reference/typescript/agents/livewire/agent-session

[functiontool]: /docs/server-sdks/reference/typescript/agents/livewire/function-tool

`RunContext<UserData>` is passed to tool handler functions via the `context`
parameter's `ctx` property. It provides access to the current
[`AgentSession`][agentsession] and its user data, letting tools read and modify
session state.

```typescript {7}
import { tool, RunContext } from '@signalwire/sdk/livewire';

const savePreference = tool<{ color: string }>({
  description: 'Save the user\'s favorite color.',
  parameters: { color: { type: 'string' } },
  execute: (params, { ctx }) => {
    const data = ctx.userData as Record<string, string>;
    data.favoriteColor = params.color;
    return `Got it, your favorite color is ${params.color}.`;
  },
});
```

## **Constructor**

```typescript {1}
new RunContext<UserData>(session: AgentSession<UserData>)
```

The `RunContext` is constructed internally by `AgentSession` when dispatching tool
calls. You do not need to create it manually.

## **Properties**

**`session`** `AgentSession<UserData>`

The [`AgentSession`][agentsession] that owns this context.

---

**`userData`** `UserData`

Shortcut for `session.userData`. Returns the user data attached to the session.

---

## **Example**

```typescript {13}
import {
  Agent, AgentSession, tool, RunContext, defineAgent, runApp, JobContext,
} from '@signalwire/sdk/livewire';

interface SessionData {
  notes: string[];
}

const addNote = tool<{ note: string }>({
  description: 'Add a note to the session.',
  parameters: { note: { type: 'string' } },
  execute: (params, { ctx }) => {
    const data = ctx.userData as SessionData;
    data.notes.push(params.note);
    return `Note saved. You have ${data.notes.length} note(s).`;
  },
});

const agentDef = defineAgent({
  entry: async (ctx: JobContext) => {
    const agent = new Agent({
      instructions: 'You are a note-taking assistant.',
      tools: { addNote },
    });

    const session = new AgentSession<SessionData>({
      userData: { notes: [] },
    });

    await session.start({ agent });
  },
});

runApp(agentDef);
```

> Context object available inside tool handler functions.