AgentSkin

Context middleware for AI agents. AgentSkin removes low-value API, JSON, and terminal noise before it enters model context.

The frozen AgentSkin 5.1 offline core evaluation also has an accepted Sparse Env execution path. AgentSkin preserves the workload correctness contract while Sparse Env owns cold/warm environment selection and lifecycle; see agentskin/docs/SPARSE_ENV.md.

What it does

AgentSkin has three primary workflows:

• compress — one front door that auto-detects JSON, CLI output, or plain text.
• fetch_optimized_data — fetches a public URL and applies URL-specific pruning rules when available.
• reduce — compacts terminal output using Tokenjuice's rule-driven reducers.

Five advanced tools remain for compatibility and diagnostics: apply_json_semantic, classify_url, strip_ansi, estimate_tokens, and skin_reasoning.

Quick start

npx -y agentskin@latest

MCP config:

{
  "mcpServers": {
    "agentskin": {
      "command": "npx",
      "args": ["-y", "agentskin@latest"]
    }
  }
}

Design rule

Fidelity first, compression second. Explicit signals and URL rules are authoritative. Generic keys such as id, name, and url are only fallback signals when no explicit rule exists.

A reduction is useful only when the information required by the task survives it.

Current verification

The release gate runs the AgentSkin-owned test suite, including MCP startup/security and live HTTP integration tests. Run it with:

cd agentskin
npm ci
npm test

Benchmarks are workload-specific. The test suite prints measured reductions for its fixtures instead of claiming one universal savings percentage.

Runtime

• Node.js MCP server over stdio
• Tokenjuice is a normal npm dependency for CLI reduction
• URL-specific semantic pruning rules for structured APIs
• SSRF checks for fetches, response-size limits, rate limiting, Zod validation, and processing timeouts

Development

The npm package lives in agentskin/ inside this repository.

cd agentskin
npm ci
npm test
npm run lint
npm pack --dry-run

Credits

AgentSkin semantic pruning and MCP integration: Shawn Nichols Sr. / Nichols Transco LLC.

CLI reduction uses Tokenjuice by Vincent Koc under its MIT license.