Choose an agent runtime

A harness is the coding program that runs an agent’s session in a sandbox. It asks the model what to do, reads and writes files, runs commands, and returns a report. Choose it for project-agent tasks or an automation’s agent node; the ordinary Chat model picker does not select a harness.

Select the runtime and check access

In a project’s Agents tab, open an agent and choose Agent type. An automation’s agent node calls the field Harness. Then choose the model and provider. Under Settings > AI providers, Agent runtimes shows which execution paths the organization can currently serve.

A runtime needs both compatible credentials and sandbox capacity. A working chat model is not enough. If a runtime is missing or has no models, inspect its status and provider credential before changing the task prompt.

Compare supported runtimes

“Managed” means the runtime calls through Tale’s model gateway. “Direct” means the session receives a credential for the provider’s own tooling. The built-in definitions support these combinations; your deployment and credentials determine what is available.

To guide project work, comment on the task and mention its agent. Claude Code receives that guidance at a tool boundary. For the other runtimes, Tale stops the current process and continues the conversation in a new process with the comment. This is why a running task may restart its process after you give it direction.

Understand credential exposure and cost

With a stored API key or deployment-environment credential, Tale supplies a session-scoped gateway key. The original model-provider key stays at the platform. Calls through this gateway are metered and subject to the applicable spending rules, including allowance already assigned to other running turns.

Vendor subscriptions use their supported harness and receive the subscription credential in the session environment. They cannot be used as ordinary chat credentials or with an incompatible harness. Their direct provider calls bypass Tale’s gateway metering and spending caps; review usage with the subscription provider.

These model-credential rules do not mean the sandbox contains no secrets. Explicitly granted Secrets, and the token supplied for an equipped GitHub connection, can be available inside it. Grant only the access the task needs.

Understand files and connected tools

A project agent reuses a persistent workspace across its tasks. Task attachments are available read-only under /agent/inputs/<task>/attachments/. Files written to /agent/output/<task>/ are collected as task Deliverables when the turn ends. Automation agent output is collected from /agent/output/.

Equipped skill bundles are staged as files and named in the run’s instructions. Review their instructions and scripts before granting them; Skills on agents explains staging and visibility.

Tale’s connector broker keeps ordinary connector credentials at the platform and returns action results. It exposes read actions to agents, and refuses writes through that broker. Use an automation connector node for a governed connector write. GitHub tooling and explicitly granted secrets have their own access paths, so the broker’s read-only rule is not a general ban on all shell writes.

Outbound access normally permits package installation and repository cloning while blocking private addresses and cloud metadata targets. Operators can restrict permitted hosts further. If a command cannot reach a site, check the network policy instead of assuming the credential is wrong.

Check the result

The runtime determines when its turn is finished; Tale collects the report and output. Read both before marking the task complete. Confirm which checks actually ran and which depend on services unavailable in the sandbox. Task automation explains the review loop; execution logs explains an automation’s agent-step result.