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Configure a custom Expert

Before creating a custom Expert, check Template Experts. Template Experts are the fastest path when your workflow matches a common pattern such as PR authoring, code review, verification, feedback triage, incident investigation, project building, or ticket dispatch. Create a custom Expert when the workflow is specific to your team, requires custom tools or instructions, or combines systems in a way no Template Expert covers.
1

Define the workflow

Write down what the Expert owns, what input it expects, what output it should produce, and where a human must make a decision. Good Experts have a narrow job and a clear stopping rule.
2

Choose the runtime environment

Select an Environment with the repos, CLIs, language toolchains, and network access the Expert needs.
3

Add integrations and capabilities

Grant only the integrations the Expert needs, such as code hosting, ticketing, communication, web access, or monitoring tools.
4

Write the system prompt

Describe the Expert’s role, inputs, process, output format, allowed write operations, and handoff rules. Include idempotency checks for event-driven Experts so repeated triggers do not create duplicate comments, tickets, or sessions.
5

Configure launch guidance

Add user instructions and placeholder text that tell people what to paste when launching the Expert, such as a change request, incident channel, ticket, project brief, or PR/MR URL.
6

Add workers or triggers if needed

Attach worker Experts for delegated sub-tasks, or add triggers for code-hosting events, communication messages, schedules, or webhooks. Test the manual path first, then automate.
7

Validate with a real example

Run the Expert on a representative task, inspect the session, and tune the prompt or integrations before rolling it out to the team.

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Prompt checklist

Strong Expert prompts usually define:
  • Role and scope: what the Expert owns and what it must not do
  • Required inputs: what to ask for before taking action
  • Process: the phases it should follow, including when to stop for human input
  • Output format: the exact shape of comments, reports, tickets, or summaries
  • Allowed writes: which external actions are permitted
  • Idempotency: how to detect prior runs and avoid duplicates
  • Attribution: how messages link back to the Cosmos session that produced them
  • Memory: where reusable team learnings should be read or written, if the workflow improves over time
Experts are saved configurations, not one-off prompts. Keep them small enough to reason about, test them on real examples, and prefer composing a few specialized Experts over one very broad Expert.