A custom skill saves a process you've worked out in Agent so you can run it again on new inputs without rebuilding the chat, and share it so your team gets the same result. This article covers building a skill from a chat you've already had, writing instructions Agent can follow and sharing the skill with your workspace.
When a Skill Is Worth Making
A skill earns its place whenever the same conversation keeps coming back:
- A process you repeat with different inputs, like a new product, a new set of cities or a new character
- A process your teammates should run the same way you do, without you walking them through it
- A job where the number of outputs changes each time, like one localized ad per city, whether that's three or 30
Once created, a custom skill works just like a Runway-authored one. You trigger it, answer its questions and get the same kind of output, and you can still redirect Agent at any step.
Building a Skill From a Chat
You can write a skill from scratch, but the quickest route is to have Agent turn a finished chat into one.
- Work through the task in a regular Agent chat until the result is what you want
- In the same chat, ask Agent to turn the process into a skill, and give it a name if you have one in mind. For example:
I like how we got to these localized ads. Turn the process we followed into a skill called Localized Ads that I can run again for new cities, and have it ask me for the inputs it needs each time.
Agent saves it as a custom skill. Trigger it the same way as any other: type / and select it by name.
Where to Add Your Skill
- Select + in the Agent composer, open the Starters tab and select Skills
- Hover over Create your own skill and select Write
- Give your skill a Name and a short Description
- Paste or write your Instructions, up to 5,000 characters
- Under Sharing, keep Private or choose Share with workspace
- Select Create
Trigger your skill the same way as any other: type / and select it by name. Once sent, the chat labels your message with the skill Agent is following.
What to Put in the Instructions
Instructions work best when they tell Agent what to collect before it starts and what to hand back when it's done. Describe the steps in order, name the output you expect and include any style guidance Agent should apply every time. A localization skill, for example, might say:
- Inputs — ask the user for a finished ad image, a list of cities and a caption for each city
- Steps — for each city, adapt the setting, light and on-screen text to match the location, then generate a 9:16 version for social and a 5-second clip
- Checkpoint — share the adapted images for approval before generating any video
- Output — one image and one clip per city
Sharing a Skill With Your Workspace
Skills are Private by default, visible only to you. Choose Share with workspace in the Sharing field when you create the skill, and it becomes available to everyone in your workspace. Each teammate triggers the same skill, answers the same questions and gets the same kind of output, which is what keeps a process consistent across a team without anyone re-prompting from scratch.
Example Custom Skills
A few skills that start out as ordinary chats:
| Skill | What it asks you for | What it produces |
|---|---|---|
| Localized ads | A finished ad image, a list of cities and a caption for each | A version of the ad for each city with the setting, light and text adapted to match, as a social-ready image and a short clip |
| Recurring-character ad | Your Brand Kit, a description of the protagonist and the scenario | Character and environment images for approval, then the finished ad video in your brand's look |
| Scene variations | A character, a list of locations and a list of objects | A 15-second video for every combination of character, location and object |
FAQ
Can everyone in my workspace see my custom skills?
Only if you share them. Custom skills are set to Private by default, visible only to you. Choose Share with workspace when creating a skill to make it available to everyone in your workspace.
Can a skill produce a different number of outputs each time?
Yes. Write the instructions to ask for a list (cities, scenes, characters) and to produce one output per item, and Agent generates as many versions as you give it. This is what makes skills a good fit for batch work like localization, where the number of markets changes from one run to the next.
How long can a skill's instructions be?
Up to 5,000 characters. The counter under the Instructions field shows how much room you have left.
Do custom skills work differently from Runway's skills?
No. Once created, you trigger a custom skill the same way, Agent follows its instructions and checks in with you along the way, and you can redirect it or ask for variations at any step. See Using Agent Skills.
Can I edit a custom skill after creating it?
Yes. In an Agent chat, ask Agent to update the skill and describe what should change. Agent updates the existing skill, so you don't need to create a new one.