[Docs index](/docs.md) / [Tool Policies](/docs/tool-policies/overview.md) / Writing Conditions

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# Writing Conditions

Conditions let a rule look at the values inside a tool call. This guide covers how to point a condition at a value, which comparisons are available, and the behaviors that are easy to get wrong.

## Before you begin

- You must be a workspace admin.
- Open a rule in the editor. See [Creating a rule](creating-a-rule.md).
- It helps to have an example of a real call. You can start a rule from one in Tool History. See [Creating a rule from a tool call](creating-a-rule-from-a-tool-call.md).

## How a condition is built

Each condition has three parts:

- **Path**: which value in the call to look at.
- **Operator**: how to compare it.
- **Value**: what to compare it against.

A rule can have several conditions. All of them must match for the rule to apply.

## Steps

### 1. Add a condition

In the rule editor, click **Add condition**.

### 2. Choose the path

Click the **Path** field and press **Tab**. When the rule targets a single tool, the list shows that tool's parameters with their type and whether they are required. Press **Tab** to move through the list and **Enter** to choose.

You can also type a path yourself:

| Path | What it points at |
|------|-------------------|
| `query` | The parameter named `query` |
| `options.limit` | `limit` inside `options` |
| `to[0].email` | The `email` of the first item in `to` |
| `to[*].email` | The `email` of every item in `to` |
| `$` | The whole call |

If you type a path that is not one of the tool's parameters, the editor shows a warning under the field. You can still save the rule, but check the name. A condition on a parameter the tool does not have will never match.

Parameter suggestions need a single tool. When the target is a pattern or is left blank, the path is plain text.

### 3. Choose the operator

The **Operator** list narrows to what makes sense for the parameter you chose.

| Parameter type | Operators offered |
|----------------|-------------------|
| Text | equals, not_equals, contains, starts_with, ends_with, matches, in, not_in, exists, missing |
| Web address | url_host_not_in and url_host_in first, then the text operators |
| Number | equals, not_equals, gt, gte, lt, lte, in, not_in, exists, missing |
| True or false | equals, not_equals, exists, missing |
| Fixed set of choices | equals, not_equals, in, not_in, exists, missing |
| List | array_size_gt, exists, missing |

What each operator does:

| Operator | Matches when |
|----------|--------------|
| equals / not_equals | The value is, or is not, exactly this |
| contains | The text includes this |
| starts_with / ends_with | The text begins or ends with this |
| matches | The text fits a pattern (regular expression) |
| in / not_in | The value is, or is not, one of a list |
| gt, gte, lt, lte | The number is greater than, at least, less than, or at most this |
| url_host_in / url_host_not_in | The web address is, or is not, on one of these hosts |
| array_size_gt | The list has more items than this |
| exists / missing | The value is present, or absent |

### 4. Enter the value

The **Value** field changes with the parameter type:

- True or false parameters show a choice of `true` or `false`.
- Parameters with a fixed set of choices show those choices. For **in** and **not_in**, you can pick several.
- Number parameters take a number.
- List operators take values separated by commas.

Tick **ignore case** to treat uppercase and lowercase as the same. It is offered for text comparisons only.

### 5. Test it

Enter an example in **Params JSON** under **Test conditions** and click **Run test**. Each condition reports whether it matched and what value it found.

![A condition on a number parameter with operators narrowed to number comparisons](screenshots/typed-conditions.png)

## Behaviors to know

### Text is matched exactly as typed

**contains**, **equals**, **starts_with**, and **ends_with** treat every character literally. An asterisk in the value is looked for as an asterisk. It is not a wildcard.

To match a pattern, use the **matches** operator. For example, to match any text that includes `foo bar baz` followed by anything, use `foo bar baz.*`. Patterns match anywhere in the text unless you anchor them with `^` at the start or `$` at the end.

Wildcards with `*` work only in the **Tool pack** and **Tool** fields of the target.

### Matching is case sensitive by default

`DROP TABLE` does not match a **contains** condition for `drop table` unless **ignore case** is ticked. For rules that guard against something, tick it.

### A dot in a pattern does not cross lines

In a **matches** pattern, `.` stands for any character except a line break. A query written across several lines will not match `select.*from secrets`. Use `[\s\S]*` in place of `.*` when the text can contain line breaks.

### Patterns are checked for safety

Some patterns can take a very long time to evaluate. The editor rejects patterns with nested repetition such as `(a+)+`, patterns that refer back to an earlier group, and patterns that are too long.

### Negative operators need a value to be present

**not_equals**, **not_in**, and **url_host_not_in** match only when the parameter is present in the call. If the call leaves the parameter out, they do not match.

If a parameter is optional and you want to block calls that omit it, add a second rule with the **missing** operator.

### Host lists match the whole host

`acme.com` matches `acme.com` only. To include subdomains such as `api.acme.com`, start the entry with a dot: `.acme.com`.

With **url_host_not_in**, a value that is not a valid web address counts as off the list. A rule that blocks every host except the ones you list also blocks `evil.com/path` and other malformed addresses.

### Lists match if any item matches

With a path such as `to[*].email`, positive operators match when any item matches. Negative operators match only when every item does.

## Next steps

- [Using a tool as a classifier](using-a-classifier.md)
- [Testing rules with the simulator](testing-rules-with-the-simulator.md)
- [Troubleshooting](troubleshooting.md)

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## Navigation

### In this section: Tool Policies

- [Tool Policies](/docs/tool-policies/overview.md)
- [Use Cases and Playbooks](/docs/tool-policies/use-cases.md)
- [Creating a Rule](/docs/tool-policies/creating-a-rule.md)
- **Writing Conditions** (current)
- [Using a Tool as a Classifier](/docs/tool-policies/using-a-classifier.md)
- [Testing Rules with the Simulator](/docs/tool-policies/testing-rules-with-the-simulator.md)
- [Creating a Rule from a Tool Call](/docs/tool-policies/creating-a-rule-from-a-tool-call.md)
- [Managing the Rule List](/docs/tool-policies/managing-the-rule-list.md)
- [Troubleshooting](/docs/tool-policies/troubleshooting.md)

#### Playbooks

- [Playbook: Build a Query Intent Classifier](/docs/tool-policies/playbook-query-intent-classifier.md)
- [Playbook: Control Where Your Tools Can Send Data](/docs/tool-policies/playbook-outbound-request-allowlist.md)
- [Playbook: Give a Scheduled Agent Only the Access It Needs](/docs/tool-policies/playbook-scheduled-agent-guardrails.md)
- [Playbook: Put Guardrails on Warehouse Queries](/docs/tool-policies/playbook-warehouse-query-guardrails.md)

### Other sections

- [Tool Creation](/docs/tool-creation/overview.md)
- [Subagents](/docs/subagents/overview.md)
- [Agent Skills](/docs/agent-skills/overview.md)
- [Sandcastles](/docs/sandcastles/overview.md)
- [MCP Servers](/docs/mcp-servers/overview.md)
- [Scheduled Triggers](/docs/scheduled-triggers/overview.md)
- [Agent Filesystem](/docs/agent-filesystem/overview.md)
- [Workspace Permissions](/docs/workspace-permissions/overview.md)
- [Workspace Billing](/docs/workspace-billing/overview.md)
- [Chat Sharing](/docs/chat-sharing/overview.md)

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