Why we don't have any examples for Python. It's so frustrating.

[garg10may]

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Question Category

• Protocol Specification
• SDK Usage
• Server Implementation
• General Implementation
• Documentation
• Other

Your Question

I see fastMcp doesn't have support for _meta tag but works with meta. Is it correct functionality? Has everybody stopped working with python, each example is about react, js, ts, solid, svelte etc.
@mcp.tool(
meta={
"ui": {"resourceUri": VIEW_URI}
}
)

[Michael-WhiteCapData]

meta= is the correct FastMCP Python API. Python identifiers cannot be named _meta in that decorator's public signature, and FastMCP serializes meta as the protocol tool's _meta field.

@mcp.tool(
    meta={
        "ui": {
            "resourceUri": VIEW_URI,
            "visibility": ["model", "app"],
        }
    }
)
async def my_tool():
    ...

You can verify the wire shape by running fastmcp inspect server.py --format mcp or looking at tools/list in MCP Inspector; the returned tool should contain:

{
  "_meta": {
    "ui": {
      "resourceUri": "ui://..."
    }
  }
}

Linking the tool is only half of the App. The server also needs to serve VIEW_URI as a ui:// resource whose MIME type is text/html;profile=mcp-app.

The older flat _meta["ui/resourceUri"] form is deprecated; nested _meta.ui.resourceUri is current. The ext-apps browser bridge examples are necessarily JavaScript/TypeScript because they run in the iframe, but the MCP server can be Python. A small end-to-end Python server example in this repository would still be a useful documentation contribution.