ext-skills/docs/approaches.md

Approaches Being Explored

These are not mutually exclusive solutions.

1. Skills as MCP Primitives

Add Agent Skills as a first-class, discoverable primitive in MCP. A skill is a named bundle of instructions plus references to tools, prompts, and resources that together teach an agent how to perform a domain-specific workflow.

Proposal: SEP-2076

Author: Yu Yi

2. Skills as Registry Metadata

Add skill references to MCP registry entries so users know to install associated skills alongside servers.

Implementations:

• Ozz started a discussion around skills.json format proposal
• NimbleBrain has implemented this via a skill field in registry _meta, supporting .skill artifact bundles (ZIP containing SKILL.md + manifest.json).
  • https://github.com/NimbleBrainInc/skills
  • registry.nimbletools.ai

3. Skills as Tools

Expose skills via tools like list_skills and read_skills. Server instructions can direct the agent to call the skill tool first.

Implementations:

• skilljack-mcp
• skills-over-mcp

This approach may also:

• Expose skills as MCP resources
• Use Prompts for explicit skill invocation
• Use tools/listChanged and other notifications for dynamic updates without server re-initialization

Variant: Skills via Sampling

Instead of exposing skill tools to the main agent, use MCP's Sampling with Tools capability (SEP-1577). The server requests a sampling call with skill-specific tools (read_skill_md, execute_script, etc.) that are only visible during that sampling request. This keeps skill tools hidden from the main agent, addressing tool bloat. The server orchestrates skill execution; the main agent just sees the result.

Caveat: Sampling has limited client support currently.

Source: jbnitorum

4. Gateway/Composition Pattern

A gateway-style server that provides a group of MCPs as one, ensuring they get requisite configuration and instructions to work in harmony.

This pattern could enable loading primitives (tools) without the full "server" boundary.

Community input:

"MCP repos can also be used as libraries... a gateway in same language as bundle servers could also load primitives like tools, and not necessarily need or want the 'server' parts." SamMorrowDrums

5. Server Instructions Reference

Use server instructions as a pointer to a resource: "If you need to do X, fetch resource Y for further instructions." This defers loading skill content until needed, managing context more efficiently.

Limitation: May not work with off-the-shelf servers where you can't modify their instructions.

6. Official Convention as Intermediate Step

A documented "MCP Skills Convention" as a middle path between ad-hoc experiments and protocol extension. This could:

• Define well-known URI schemes or naming patterns (e.g., resources matching **/SKILL.md)
• Recommend metadata structure (version, tags, dependencies) aligned with agentskills.io
• Provide guidance on control model: resources for application-controlled, skill() tool for model-controlled
• Be documented in MCP docs as a "Pattern" — not in protocol schema, but officially recommended
• Allow data gathering on adoption before considering protocol-level changes

This mirrors how other ecosystems (e.g., Kubernetes) graduate patterns: start as convention, prove value, then formalize. Could be a concrete IG deliverable: "MCP Skills Convention v0.1."