“Instructions” option to server - what is that?

[nanandn]

Question

What is the “instructions” server initialization option? Where is it used?

Is there any explanation and/or example? Could not find anything about it.

Thanks

Additional Context

No response

[pja-ant]

There's some info in the schema spec: https://modelcontextprotocol.io/specification/2025-06-18/schema#initializeresult

Instructions describing how to use the server and its features.

This can be used by clients to improve the LLM’s understanding of available tools, resources, etc. It can be thought of like a “hint” to the model. For example, this information MAY be added to the system prompt.

[akolotov]

It makes sense to keep in mind that some MCP Host just skip the MCP server instructions.