> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Prompt Injection Protection

> Automatic safety wrapping for results from external/untrusted tools

Web search and other external tools wrap results in safety markers — the model treats them as data, not instructions.

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents import Agent
from praisonaiagents.tools import duckduckgo

agent = Agent(
    name="Researcher",
    instructions="Research topics safely",
    tools=[duckduckgo],
)

agent.start("Find recent AI safety papers")
# duckduckgo results auto-wrapped in <external_tool_result> markers
```

The user searches the web; external tool output is wrapped so the model treats it as data.

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph LR
    subgraph "Trust-Aware Tool Execution"
        Call[🛠️ Tool call] --> Check{🔍 External?}
        Check -->|Trusted| Pass[⚡ Pass through]
        Check -->|External| Wrap[🛡️ Wrap in markers]
        Wrap --> Safe[✅ Safe result]
        Pass --> Safe
    end

    classDef tool fill:#8B0000,stroke:#7C90A0,color:#fff
    classDef check fill:#F59E0B,stroke:#7C90A0,color:#fff
    classDef wrap fill:#189AB4,stroke:#7C90A0,color:#fff
    classDef result fill:#10B981,stroke:#7C90A0,color:#fff

    class Call tool
    class Check check
    class Wrap,Pass wrap
    class Safe result
```

## Quick Start

<Steps>
  <Step title="Simple Usage">
    Built-in search tools are protected automatically:

    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    from praisonaiagents import Agent
    from praisonaiagents.tools import duckduckgo

    agent = Agent(
        name="Researcher",
        instructions="Research topics safely",
        tools=[duckduckgo],
    )

    agent.start("Find recent AI safety papers")
    ```
  </Step>

  <Step title="With Configuration">
    Mark custom tools as external:

    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    from praisonaiagents import Agent, register_tool

    def my_web_lookup(query: str) -> str:
        """Fetch data from an external API."""
        return fetch_from_api(query)

    register_tool(my_web_lookup, name="my_web_lookup", trust_level="external")

    agent = Agent(
        name="Researcher",
        instructions="Use my_web_lookup for facts",
        tools=["my_web_lookup"],
    )
    ```
  </Step>
</Steps>

***

## How It Works

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
    participant Agent
    participant Tool as External tool
    participant Trust as Trust layer
    participant LLM

    Agent->>Tool: Execute
    Tool-->>Trust: Raw result
    Trust-->>Agent: Wrapped in markers
    Agent->>LLM: Treat as factual data only
```

Auto-protected built-ins include `duckduckgo`, `web_search`, `tavily_search`, `scrape_page`, `fetch_url`, and others in the external tools set. MCP tools can be marked at registration time.

| Condition                     | Action                              |
| ----------------------------- | ----------------------------------- |
| Trusted tool                  | Result unchanged                    |
| External + string ≥ 32 chars  | Wrapped in `<external_tool_result>` |
| External + string \< 32 chars | Unchanged (overhead skip)           |
| External + dict/list          | JSON-serialised then wrapped        |

***

## Configuration Options

| Option                            | Type                        | Default     | Description                                         |
| --------------------------------- | --------------------------- | ----------- | --------------------------------------------------- |
| `trust_level`                     | `"trusted"` \| `"external"` | `"trusted"` | Set on `register_tool(..., trust_level="external")` |
| `MIN_CONTENT_LENGTH_FOR_WRAPPING` | `int`                       | `32`        | Minimum string length before wrapping               |

***

## Best Practices

<AccordionGroup>
  <Accordion title="Mark external data sources as external">
    Web APIs, scraping, MCP servers you do not control, and third-party feeds should use `trust_level="external"`.
  </Accordion>

  <Accordion title="Do not strip safety markers">
    Removing `<external_tool_result>` tags breaks the model's boundary between data and instructions.
  </Accordion>

  <Accordion title="Prefer external when unsure">
    Wrapping cost is minimal; under-marking exposes you to injection.
  </Accordion>

  <Accordion title="Layer with other guards">
    Combine with [Tool Circuit Breaker](/docs/features/tool-circuit-breaker) and input validation for defence in depth.
  </Accordion>
</AccordionGroup>

***

## Related

<CardGroup cols={2}>
  <Card title="Tool Circuit Breaker" icon="shield-exclamation" href="/docs/features/tool-circuit-breaker">
    Automatic tool failure detection and recovery
  </Card>

  <Card title="Security Overview" icon="shield" href="/security">
    Complete security features and best practices
  </Card>
</CardGroup>