Orchestration Skills

Orchestration Skills define the coordination layer through which a higher-level request is decomposed into bounded calls to other skills. Their role is to keep multi-step work inside an explicit execution contract rather than leaving decomposition, delegation, and session choice to ad hoc prompt behavior.

Structured Coordination of Reusable Skills

Some requests are not difficult because one local operation is complex, but because the work must be distributed across several capabilities under stable restrictions. In such cases, a single skill should not improvise the whole coordination path and the top-level agent should not repeatedly reconstruct the same workflow from scratch. The architectural need is therefore not only better prompting, but a governed coordination layer in which admissible downstream capabilities, preparation steps, and session discipline are made explicit.

Orchestration Skills address this need by treating coordination as a separate runtime concern. In AchillesAgentLib, an orchestration skill is not a generic narrative about a workflow. It is a localized execution contract that specifies how bounded delegation should occur and which downstream skills may participate. This makes orchestration inspectable, reusable, and easier to stabilize across repeated runs.

These skills are defined in oskill.md. The descriptor is the human-maintained source, but its role is operational rather than descriptive. When the subsystem prepares a skill, it extracts the recognized sections, normalizes the declared allowlists, and records the execution configuration that will govern the later session. The practical authoring rules, together with a minimal template and a fuller example, are discussed in Authoring.

How Orchestration Skills Execute in Practice

At execution time, the subsystem resolves the downstream skills admitted by the descriptor, wraps them through the shared MainAgent, and starts either a loop session or a SOP session. The orchestration skill therefore does not perform the domain work directly. It establishes the controlled execution environment within which other skills may be invoked.

The session choice is deliberately narrow. If the resolved session value is loop, the subsystem starts a loop-based agentic session. In every other case, it falls back to a SOP session. When a preparation section exists, it becomes a bounded context-building stage for that session. The runtime path, the tool wrapping model, the allowlist behavior, and the loop-specific session persistence model are examined in Runtime.

The filesystem footprint for this skill family remains minimal. Discovery only requires a directory containing oskill.md. The governing behavior resides in the descriptor and in the orchestration subsystem rather than in a generated runtime file.

Minimal orchestration layout

  • skills/
    • documentation-orchestrator/
      • oskill.md
Note

Unlike DBTable Skills, orchestration skills do not rely on a family-specific generation pipeline. Their operational behavior is derived directly from the parsed descriptor and from the subsystem that executes it.