Dynamic content reference

Templates are text with {{ }} expressions that are resolved when an agent runs. This page lists where templates are accepted, what they can read, and every function. For an introduction, see Dynamic content. Templates use Go’s text/template syntax with the default {{ }} delimiters.

Where templates are accepted

Place	Functions available
A sub-agent’s system prompt and user prompt	All
An action tool’s fields	All
A context step’s fields	All
A guard’s expression	All except `tool_param`. A guard never sees the model’s arguments.
An entry handler’s settings	`secret` only. Settings are resolved when configs load, not on each run.
An MCP tool’s settings	`secret` only

Reading the message

What is available depends on the entry the run came in through.

Entry	Functions	Variables
Webhook	`body`, `param`, `header`, `urlparam`	none
`github_webhook`	`body`, `param`, `header`, `urlparam`	`.github.*`
`telegram_webhook`	`body`, `param`, `header`, `urlparam`	`.telegram.*`
`discord_gateway`	none. Using one is a template error, because a Discord run has no HTTP request.	`.discord.*`
Trigger, run by hand or handed a task	`input`, `trigger_value`	none
Trigger, run on a schedule	none. `input` and `trigger_value` are not defined on a scheduled run.	none

The Available entry handlers lists every variable of each handler.

Request functions

Function	Returns	Example
`body(path)`	A field of the JSON request body, by dot and array path. An empty path returns the whole body. Reads only when `Content-Type` is exactly `application/json`.	`{{ body "user.id" }}`
`param(name)`	A query-string or form parameter.	`{{ param "page" }}`
`header(name)`	A request header.	`{{ header "Authorization" }}`
`urlparam(name)`	A variable declared in the entry’s path, such as `{userId}` in `/users/{userId}`.	`{{ urlparam "userId" }}`

Trigger functions

Function	Returns	Example
`input(key)`	An input the run was started with. An Agent Task Tool starts its agent with the model’s instruction as `instruction`.	`{{ input "instruction" }}`
`trigger_value(key)`	The same value, always as a string. Empty when absent.	`{{ trigger_value "instruction" }}`

Available from any entry

Expression	Returns	Example
`.stepID`, `.stepID.field`	The output of an earlier context step or action, by its id.	`{{ .customer.name }}`
`action(name)`	The same output, looked up by step id, then by display name.	`{{ action "customer" }}`
`secret(name)`	A stored secret, or the environment variable of the same name. See Secrets.	`{{ secret "weather-api-key" }}`
`tool_param(name)`	An argument the model passed to the tool. Available in an action tool’s fields, and in the prompts of a sub-agent called by a Call sub-agent tool that declares `params`.	`{{ tool_param "question" }}`

Transform functions

Function	Returns	Example
`tostring(value)`	The value as a string. `nil` gives an empty string. Anything that is not a plain value is given as JSON.	`{{ tostring (body "count") }}`
`jsonout(value)`	The value as JSON. A string is escaped and returned without surrounding quotes, so it can sit inside a JSON template.	`{"q": "{{ jsonout (body "q") }}"}`
`jsonraw(value)`	The value as JSON. A string keeps its surrounding quotes.	`{{ jsonraw .customer }}`
`strip(text, prefix)`	`text` with a leading `prefix` removed, then trimmed of surrounding whitespace.	`{{ strip (header "Authorization") "Bearer" }}`
`escape(text)`	`text` with quotes, backslashes, and control characters escaped. Anything that is not a string gives an empty string.	`{{ escape (body "note") }}`
`join(list, separator)`	The list’s strings joined. A list with any element that is not a string is returned unchanged.	`{{ join .tags ", " }}`
`pluck(item, key)`	From a map, the value at `key`. From a list of maps, a list of each map’s value at `key`.	`{{ pluck .users "email" }}`
`hash(value)`	The MD5 hash of the value, as lowercase hex.	`{{ hash (body "email") }}`
`now()`	The server’s local time, as `2006-01-02 15:04:05`.	`{{ now }}`

Condition functions

Used mainly in guards. Each returns true or false.

Function	True when	Example
`eq(a, b)`, `ne(a, b)`	The values are equal, or not equal.	`{{ eq (body "plan") "pro" }}`
`lt`, `le`, `gt`, `ge`	`a` is less than, at most, greater than, or at least `b`.	`{{ gt (len .orders) 0 }}`
`empty(value, title)`	The value is empty.	`{{ empty (body "id") "id" }}`
`notempty(value, title)`	The value is a non-empty string, map, or list. The string `"null"` counts as empty.	`{{ notempty (body "id") "id" }}`
`email(value, title)`	The value is a valid email address.	`{{ email (body "email") "email" }}`
`bcrypt(value, hash, title)`	The value matches the bcrypt hash.	`{{ bcrypt (body "password") .user.hash "password" }}`

title names the value being checked. It has no effect on a guard’s result.

Built into the template language

Construct	Use	Example
`if`, `else`, `end`	Show text only when a value is set or a condition is true.	`{{ if .discord.is_super_user }} (the owner){{ end }}`
`range`, `end`	Repeat text for each item of a list.	`{{ range .orders }}{{ .id }} {{ end }}`
`with`, `end`	Work inside one value.	`{{ with .customer }}{{ .name }}{{ end }}`
`and`, `or`, `not`	Combine conditions.	`{{ and .discord.is_super_user (not .discord.is_bot) }}`
`len`, `index`	The length of a list, and one item of it.	`{{ index .orders 0 }}`
`printf`	Format a string.	`{{ printf "%s-%v" .customer.name .customer.id }}`
`\|`	Pass a value to the next function as its last argument.	`{{ body "email" \| hash }}`

See Go’s text/template documentation for the rest.

Missing values and unknown functions

A variable or field that does not exist renders as an empty string.
A secret whose name matches nothing renders as an empty string.
A function that is not defined is a template error. In a guard, the config is refused when it is saved. In a prompt, the run fails.

Dynamic content

An introduction to templates, in plain language.

Available entry handlers

Every variable each handler provides.

Tools

Guards and action tool fields, which take templates.

Secrets

How secret looks a value up.

Getting started

Guides

Concepts

References

Where templates are accepted

Reading the message

Request functions

Trigger functions

Available from any entry

Transform functions

Condition functions

Built into the template language

Missing values and unknown functions

Dynamic content

Available entry handlers

Tools

Secrets

​Where templates are accepted

​Reading the message

​Request functions

​Trigger functions

​Available from any entry

​Transform functions

​Condition functions

​Built into the template language

​Missing values and unknown functions

​Related

Dynamic content

Available entry handlers

Tools

Secrets

Where templates are accepted

Reading the message

Request functions

Trigger functions

Available from any entry

Transform functions

Condition functions

Built into the template language

Missing values and unknown functions

Related