Introduction
What AI Agent Skills are and how FastGPT implements them.
What is an AI Agent "Skill"?
Under the latest ecosystem designs of mainstream AI providers, a "Skill" is defined as a persistent, reusable, and modular workflow and capability package.
For example, to compare two complex financial spreadsheets and generate an analysis, package the calculation code and report template into a Skill. In later chats, upload the spreadsheets and let the Agent use the Skill to calculate the results and format the report.
Core Design Philosophy: From Tools to Skills
An Agent combines three kinds of capability:
- Brain: Responsible for reasoning and planning (the LLM itself).
- Tools: Simple execution interfaces (such as sending a web request or running a temporary line of code), resembling the AI's "hands and feet".
- Skills: Providing the complete "operational knowledge and professional logic" (Know-how).
A skill is typically a modular package encapsulating instruction markdown (how to do it) and executable scripts (actually doing it). If a tool is a "screwdriver" in your toolbox, then a skill is a "furniture assembly guide". The AI can automatically grab this guide from its skill library based on the current context, execute the code inside a background sandbox, and complete the complex assembly.
Skills in FastGPT
Following the industry-standard design of Skills, FastGPT provides you with a "dedicated code execution workspace" featuring the following core designs:

1. Isolated Secure Runtime Sandbox
Each created skill during editing runs in a fully isolated, secure sandbox environment (powered by Sealos Devbox, OpenSandbox, etc., in the backend). All operations are restricted within this workspace to ensure safety.
2. Instant Hot-Reloading Debugging
Provides an online debugging environment integrating a file tree, code editor, and console terminal. Equipped with an agent debug panel on the left supporting hot reloading, allowing you to troubleshoot the skill before publishing.
3. Isolation of Production & Debugging
Edits in the workspace will only take effect instantly in the "Debug Chat" area. Publish a version to apply the changes to production Agents and Workflows.
4. Auto-Sleep & Seamless Invocation
For long-inactive skills, the system automatically shuts down the sandbox and performs cold-archiving to storage. When editing resumes or an Agent calls the Skill, the system restarts the sandbox and restores its archived state. Runtime charges pause while the Skill is asleep.
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