fastmcp.server.providers.prefab_synthesis

On-demand Prefab renderer resource synthesis.

Tools marked as Prefab (via app=True, PrefabAppConfig, etc.) carry a placeholder meta.ui.resourceUri and optionally a hash in meta.fastmcp._tool_hash. This module synthesizes per-tool renderer resources on demand at list_resources and read_resource time without storing or materializing anything.

Each tool's resource URI is ui://prefab/tool/<hash>/renderer.html where the hash comes from the tool's own meta (set at registration from the app name + tool name). CSP on the resource is the tool's meta.ui.csp merged with the renderer defaults across all four *_domains fields.

Functions

synthesize_prefab_resources ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/providers/prefab_synthesis.py#L200" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

synthesize_prefab_resources(server: FastMCP) -> list[Resource]

Return fresh synthetic Prefab resources for all prefab tools. Pure.

synthesize_prefab_resource_by_uri ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/providers/prefab_synthesis.py#L215" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

synthesize_prefab_resource_by_uri(server: FastMCP, uri: str) -> Resource | None

Intercept a Prefab renderer URI and synthesize on demand.

rewrite_tool_meta_for_wire ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/server/providers/prefab_synthesis.py#L228" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

rewrite_tool_meta_for_wire(tool: Tool) -> Tool

Return a model_copy with the per-tool URI and CSP stripped.

Reads the hash from the tool's own meta. If no hash is found, returns the tool unchanged. Produces a fresh copy — the original Tool object is untouched.