skill-retrieval-mcp

Semantic search over a licence-vetted corpus of 374 agent skills, served to your coding agent over MCP. Runs locally, answers in single-digit milliseconds, makes zero API calls.

Works with Claude Code, Codex CLI, Gemini CLI, Cursor, OpenClaw, Hermes, and any MCP-compatible agent.

You: "Deploy this service to GKE"

─── Step 1: the agent searches ───────────────────────────────────────

Agent: search_skills("deploy a containerised service on kubernetes")   ← 6ms
     → 5 results (summaries only, no full instructions):
       1. "gke-service-networking"   (0.56) - Gateway API, Ingress, Cloud Armor, NEGs, managed SSL
       2. "gke-workload-scaling"     (0.51) - HPA and VPA for GKE workloads
       3. "gke-manifest-generation"  (0.51) - Production-ready Kubernetes YAML for Autopilot/Standard
       4. "gke-app-onboarding"       (0.46) - Containerizing and deploying an app to GKE for the first time
       5. "gke-basics"               (0.44) - Cluster provisioning, credentials, Autopilot vs Standard

─── Step 2: it reads the descriptions and picks #4, not #1 ───────────

Agent: get_skill("gke-app-onboarding")
     → gets the full guide: containerization, manifests, migration path
     → writes the Dockerfile and deployment.yaml

─── Step 3: a new need emerges mid-task ──────────────────────────────

Agent: # the service has to survive traffic spikes — search again
       search_skills("autoscale pods on cpu and memory")               ← 6ms
     → "gke-workload-scaling" (0.61) - Horizontal and Vertical Pod Autoscaler for GKE
     → reads the guide, adds the HPA manifest

Both searches are real output from the shipped corpus, not an illustration. Three things in it are the whole design:

• Search returns summaries, not instructions. Five summaries cost a few hundred tokens; the one skill the agent actually reads costs about 2,400.
• The top hit is not always the right one. The agent picked #4 because its description says for the first time — a judgement no ranking can make. That is why search hands back descriptions instead of injecting the winner.
• The agent searches again as the task evolves. Neither "autoscale" nor "pods" appeared in what the user asked for.

Installation

pip install "skill-retrieval-mcp[local,hf]"
skill-mcp pull --include-index      # corpus + pre-built vector index
skill-mcp init                      # detect and register with your agents

About two minutes, mostly download. init finds the agents you have installed and writes their config for you.

{
  "mcpServers": {
    "skill-retrieval": {
      "command": "/absolute/path/to/skill-mcp",
      "args": ["--data-dir", "/absolute/path/to/data-dir", "serve"]
    }
  }
}

Why search instead of install

Installing skills by hand works, right up until it doesn't scale:

• You don't know what exists. You install the ten you happen to find. Everything else, the agent guesses at.
• You can't install what you can't name. Mid-task the agent needs a skill for "OIDC-based PyPI publishing" — you would never have thought to add it.
• A skill library doesn't fit in the prompt. Lazy loading still puts every skill's name and description in front of the model: 37K tokens for this corpus before it has read a single one. The instructions are another 960K.

On 43 held-out queries phrased the way an agent would phrase a task — never echoing a skill's own name — the shipped corpus answers 81.4% at rank 1 and 90.7% within the top 3. The harness is in the repo; see dev.md for what it measures and what it found.

What's in the corpus

374 skills from eight repositories whose licences were read before anything was imported:

Each skill is a step-by-step guide with code examples, pitfalls and recommendations — not a one-liner. The median runs about 9,600 characters.

Every row records the repository it came from, its upstream URL and its SPDX licence, so anything you get back can be traced and attributed. Repositories without a licence permitting redistribution are not imported, however good the content.

skill-mcp status shows what you have locally.

Tools

Search returns summaries only. The agent calls get_skill for the ones it actually wants, which is where the token saving comes from.

Adding your own skills

<!-- ~/my-skills/deploy-checklist/SKILL.md -->
---
name: "deploy-checklist"
description: "Pre-deployment verification checklist for production releases"
tags: ["deployment", "production", "checklist"]
---

## Steps

1. Run full test suite...
2. Check database migrations...

skill-mcp import --source directory --path ~/my-skills/

The index updates automatically — new skills are searchable immediately, and only the new ones are embedded. Pass --no-index to skip that when you are batch-importing several sources before one build. Your skills merge with the corpus; deduplication is automatic.

Configuration

Everything lives in one data directory, ~/.skill-mcp by default:

~/.skill-mcp/
├── config.yaml
├── skills.db          # SQLite + FTS5
└── index/             # FAISS

Point somewhere else with the global --data-dir flag or SKILL_MCP_DATA_DIR. The flag belongs to the group, so it goes before the subcommand:

skill-mcp --data-dir /srv/skills pull

Embedding backends

The default is sentence-transformers/all-MiniLM-L6-v2 — local, free, no API key, and the one the pre-built index was built with.

An index is only valid for the model that built it, so switching means rebuilding:

# set backend: openai, model: text-embedding-3-large in config.yaml, then
skill-mcp build-index --backend openai

CLI reference

skill-mcp [--data-dir DIR] [--log-level LEVEL] COMMAND [ARGS]

  init [--data-dir DIR] [--no-register]        Set up the data directory, register with agents
  pull [--replace] [--include-index]           Download the corpus from HuggingFace
  import --source SOURCE --path PATH           Import your own skills
       [--no-index]
  build-index [--backend B] [--model M]        Build or update the vector index
       [--force]
  serve [--transport stdio|sse]                Start the MCP server
  search QUERY [--k N]                         Search from the terminal
  status                                       Show what is loaded
  dedup                                        Remove cross-source duplicates

Contributing

Issues and pull requests are welcome at github.com/JayCheng113/skill-retrieval-mcp. dev.md documents the architecture and the reasoning behind the design decisions, including what was tried and rejected — read it before a non-trivial change.

To propose a repository for the corpus, open an issue with its licence and a case for what it covers that the current 374 do not. The bar is in dev.md: a licence that permits redistribution, and evidence the skills actually win queries.

git clone https://github.com/JayCheng113/skill-retrieval-mcp
cd skill-retrieval-mcp
pip install -e ".[all,dev]"
pytest tests/ -v    # 240 tests, ~6s

License

MIT — see LICENSE.