OpenClaw Code Deep Dive Part 2: Skills, Memory & Tools

In Part 1 we covered OpenClaw’s gateway-centric architecture and discovered that the core agent loop is delegated to an external library. Now let’s look at what OpenClaw builds on top of that: skills, memory, tools, and the plugin system.

• Part 1: Architecture
• Part 2 (this post): Skills, Memory & Tools
• Part 3: Security, Quality & Verdict

Skills: Prompts, Not Code

Location: src/agents/skills/ (16 files) + skills/ (52 bundled skills)

OpenClaw’s skill system is its most distinctive design choice. Skills are Markdown files, not executable code. Each skill is a directory containing a SKILL.md with YAML frontmatter.

How Injection Works

The system prompt only includes skill names and descriptions — not the full content:

## Skills (mandatory)
Before replying: scan <available_skills> <description> entries.
- If exactly one skill clearly applies: read its SKILL.md, then follow it.
- If multiple could apply: choose the most specific one.
- If none clearly apply: do not read any SKILL.md.

The agent then uses the read tool to load the full skill content on-demand. This is lazy loading for context windows — only the selected skill consumes tokens.

5-Source Precedence

Skills load from five locations, with later sources overriding earlier:

Size limits are enforced per source to prevent abuse. Frontmatter metadata includes install specs (brew, node, go, uv, download) and invocation policies.

52 Bundled Skills

The bundled skills cover: 1Password, Apple Notes/Reminders, Bear Notes, browser snapshots, Canvas, coding agent, Discord, GitHub/Issues, image generation (OpenAI), Notion, Obsidian, Slack, Spotify, Trello, voice calls, weather, and more.

Each skill essentially teaches the agent how to use a specific tool or service — via natural language instructions, not API bindings.

Memory: Hybrid Vector + FTS Search

Location: src/memory/ (78 files)

Architecture

The memory system combines vector embeddings and full-text search (FTS), backed by SQLite + sqlite-vec.

interface MemorySearchManager {
  search(query, opts?): Promise<MemorySearchResult[]>;
  readFile(params): Promise<{text, path}>;
  status(): MemoryProviderStatus;
  sync?(params?): Promise<void>;
}

Embedding Provider Chain

Four embedding providers with automatic fallback:

In auto mode: try local first, then OpenAI, Gemini, Voyage. If all fail, degrade to FTS-only. The system never crashes on embedding failure.

Hybrid Merge Algorithm

1. Combine vector and keyword results by ID (union merge)
2. Compute weighted score: vectorWeight * vectorScore + textWeight * textScore
3. Apply temporal decay (recency boost for recently modified files)
4. Apply MMR re-ranking (Maximal Marginal Relevance for diversity)

BM25 scores are normalized to 0-1 via 1 / (1 + rank). FTS queries use Unicode-aware tokenization with AND joining.

Memory as Plugin Slot

Memory is a special plugin slot — only one implementation runs at a time. The built-in memory-core registers memory_search and memory_get tools. An alternative memory-lancedb extension provides LanceDB-backed vector storage.

Tool System: 70 Files

Location: src/agents/tools/

Available Tools

Tool Policy Profiles

Four profiles control access:

Owner-only tools (like whatsapp_login) are gated to the device owner regardless of profile. Tool groups expand aliases: “filesystem” maps to read, write, edit, apply_patch.

Plugin Hook System: 20+ Lifecycle Hooks

Location: src/plugins/hooks.ts

This is where OpenClaw’s extensibility really shines. The hook system provides 20+ lifecycle points with three execution models:

Hook Categories

Execution Models

• Parallel — All hooks run concurrently. Used for observation/analytics.
• Sequential — Hooks process by priority (higher first) with result merging. Used for modification.
• Synchronous — Runs on hot paths (transcript writes). No async allowed.

Plugin Manifest

Each extension declares capabilities in openclaw.plugin.json:

{
  "id": "my-plugin",
  "channels": ["my-channel"],
  "providers": ["my-llm"],
  "skills": ["my-skill"],
  "configSchema": { ... }
}

The Plugin SDK (src/plugin-sdk/) provides channel adapter types, tool registration, CLI extension, HTTP route registration, webhook resolution, text chunking, media building, SSRF protection, and OAuth helpers.

The 37 Extensions

The messaging coverage is genuinely impressive — 20 channel adapters covering every major platform plus niche ones like Nostr, Tlon, and Zalo.

Next: Part 3 — Security, Quality & Verdict covers the Docker sandbox, security audit system, code quality assessment, ecosystem risks, and our final take.

Analysis based on OpenClaw v2026.2.18. Source: github.com/openclaw/openclaw.