A3S Code
Skills
Prompt-time skills, inline skills, and the Skill tool
Skills
Skills are reusable instructions that the harness can discover and rank.
Built-in skills, file-backed skill directories, inline skills, and
search_skills share the same discovery path.
Enable Built-Ins
const session = agent.session('/repo', {
builtinSkills: true,
});Built-in skills include code search, code review, explanation, and bug finding. Larger role-specific behavior should live in project skill files or agent definitions.
Skill Files
Store Markdown files with frontmatter in a skill directory:
---
name: release-review
description: Review release blockers and verification evidence
allowed-tools: "read(*), grep(*), bash(cargo test*)"
---
Check package metadata, changelog, release scripts, and CI status.
Return blockers first.const session = agent.session('/repo', {
skillDirs: ['/repo/skills'],
});Inline Skills
const session = agent.session('/repo', {
inlineSkills: [
{
name: 'strict-release-review',
kind: 'instruction',
content: 'Always separate blockers from nice-to-have improvements.',
},
],
});Skill Tool
search_skills finds relevant skills:
await session.tool('search_skills', {
query: 'release blockers',
limit: 5,
});Markdown skill files with allowed-tools frontmatter and inline skills are both
discoverable. Skill administration is an SDK or filesystem concern rather than
a model-visible management tool.