# How Skills Run How a skill is triggered, how the triggering message shapes it, and the prompt that drives its execution. ## Trigger paths ### `/skill-name` slash command Prefix any input with `/`: ``` /code-reviewer review the diff in this PR ``` `runtime.MatchSkill` runs inside `exec.Prepare` at execution startup (a skill passed by name is resolved in `exec.Start` instead, and fails the run when excluded or missing). When it hits, agenvoy synthesizes a `run_skill` `tool_call` and corresponding `tool_result` directly into `ToolHistories`. Since v1.1.0 that tool result carries the whole activation — the `BINDING SKILL` rules from `configs/prompts/assign_skill.md`, `skill_execution.md`, the built-in tool list and the skill body — and no system message is added, so the system prompt stays unchanged and its prefix cache survives. The slash path is strict execution: every step binds. A SKILL.md with no `ask_user` step never calls `ask_user`; a bare `/` runs on the skill's defaults from its first step. If the user passed args (`/code-reviewer review src/parser.go`), the user message strips the `/` prefix and only the args remain. With no args, the user message keeps the literal `/` so the LLM still sees the activation context. ### Natural-language activation If an agent decides a task needs a skill mid-execution, it calls `run_skill` directly. This LLM-initiated path is advisory: the tool returns the skill name, its directory and the body as reference material, and the agent takes the parts that fit rather than running every step. The `BINDING SKILL` wrapper and `skill_execution.md` apply only to the slash path. > Skill activation is designed as a **tool call** (lazy load) rather than a startup-time pre-selection — it avoids paying skill-body tokens for tasks that don't need them. ### Multi-skill in one conversation A conversation can activate multiple skills sequentially. Each activation lands as its own `run_skill` tool result in the conversation, so a later skill follows an earlier one in the tool history; none of them is written into the system prompt. ## User message is binding context `skill_execution.md` Mandatory Principle #3 (#5 before v1.0.23): the user message that triggered the skill is **binding context, not noise**. The LLM treats it as user-supplied parameters/hints to weave into the output. Concretely: - SKILL.md describes default behavior - User message overrides or augments default behavior - A bare slash command means the skill's defaults; when the user's intent conflicts with a step, the step is followed and the conflict is stated in the final output Example: `/readme-generate private MIT` — SKILL.md defines the README structure; the user message specifies private mode + MIT license, both of which override defaults. ## Skill execution prompt The execution loop is driven by `configs/prompts/skill_execution.md`, which carries the rules every skill obeys (output discipline, tool-name mapping, mandatory principles). Since v1.1.1 one of those principles is to plan before the first step: a Skill with three or more steps opens a `write_todo` checklist built from its steps as they apply to the request. Tool-name mapping example: external skills written for the Anthropic SDK may reference `AskUserQuestion`; agenvoy maps these to `ask_user` automatically through the **Tool Mapping** table in `skill_execution.md`. No alias registration in Go is needed.