Choose a harness at setup
Cloud-agent setup offers the supported harnesses, including Claude Code, Codex, OpenCode, and Oh My Pi. Model choices depend on the harness and available providers. The harness is fixed after the agent is configured. Choose another agent when you need a different harness. The same model name does not imply that every harness exposes identical capabilities. Background-task visibility and native subagent behavior depend on the harness.Change model or effort
Model and effort settings can be changed where the selected harness supports them. The interface schedules saved changes for the next prompt and can show Settings saved; waiting to apply alongside the currently applied model. Saved settings are not proof that the running agent has switched. Existing work retains its applied settings; the harness must support and accept the update. If the update remains pending or reports an unsupported operation, check the runtime status rather than assuming the new model is in use. Some harness versions cannot apply settings live. The current Claude harness cannot apply saved model/effort changes to its running session, so subsequent platform requests can remain queued while the update is pending. Treat the displayed applied settings as authoritative; changing a dropdown alone does not change a request already running.Native tools and platform tools
Harness tools operate inside the agent’s sandbox—for example, reading local files or running commands. Platform tools operate on Fractal resources and integrations. Managed harnesses run with full tool permissions inside their sandbox. The agent’s platform read/write/delete setting constrains platform operations; it does not turn the sandbox shell into a read-only environment. Connecting an integration exposes only its supported tools, with the relevant workspace access and operation permissions. Switching models does not grant new provider authorization.Web search and fetching
Managed harnesses disable their native web-search and URL-fetch tools in favor of the platform’s web search and web fetch tools. These require the platform search service to be configured. A harness having a native search feature in another product does not guarantee that feature is enabled here. If the platform service is unavailable, the agent cannot assume native search is a fallback. This setting does not itself block ordinary shell networking. External agents have their own runtime configuration; the managed-agent web service is not a general integration connection for them or for published pages.When a tool is missing or denied
Check the relevant layer:- Is the capability supported by this integration or harness?
- Is the correct connection attached to the workspace?
- Can this agent access the resource?
- Does its operation policy permit the effect?
- Does the provider account authorize the action?