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116 lines
2.6 KiB
Markdown
116 lines
2.6 KiB
Markdown
# Provider Architecture: FastMCPProvider + TransformingProvider
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**Version:** 3.0.0
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**Impact:** Breaking change - `MountedProvider` removed
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## Summary
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The monolithic `MountedProvider` was split into two focused, composable components:
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- **`FastMCPProvider`**: Wraps a FastMCP server, exposing its components through the Provider interface
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- **`TransformingProvider`**: Wraps any provider to apply namespace prefixes and tool renames
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## Why the Split?
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`MountedProvider` was doing two things:
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1. Wrapping a FastMCP server as a provider
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2. Transforming component names with prefixes
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Separating these concerns enables:
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- Reusing transformations on any provider (not just FastMCP servers)
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- Stacking transformations via composition
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- Clearer mental model
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## New API
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### FastMCPProvider
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Wraps a FastMCP server to expose it through the Provider interface:
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```python
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from fastmcp.server.providers import FastMCPProvider
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sub_server = FastMCP("Sub")
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@sub_server.tool
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def greet(name: str) -> str:
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return f"Hello, {name}!"
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# Wrap as provider
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provider = FastMCPProvider(sub_server)
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main_server.add_provider(provider)
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```
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### TransformingProvider
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Wraps any provider to apply transformations:
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```python
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# Apply namespace to all components
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provider = FastMCPProvider(server).with_namespace("api")
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# "my_tool" → "api_my_tool"
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# "resource://data" → "resource://api/data"
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# Rename specific tools (bypasses namespace)
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provider = FastMCPProvider(server).with_transforms(
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namespace="api",
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tool_renames={"verbose_tool_name": "short"}
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)
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# "verbose_tool_name" → "short"
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# "other_tool" → "api_other_tool"
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```
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### Stacking Transformations
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Transformations compose via stacking:
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```python
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provider = (
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FastMCPProvider(server)
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.with_namespace("inner")
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.with_namespace("outer")
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)
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# "tool" → "outer_inner_tool"
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```
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## mount() Uses This Internally
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`FastMCP.mount()` now creates a `FastMCPProvider` + `TransformingProvider` internally:
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```python
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main.mount(sub, namespace="api")
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# Equivalent to:
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main.add_provider(
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FastMCPProvider(sub).with_namespace("api")
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)
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```
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## Breaking Changes
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### MountedProvider Removed
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```python
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# Before (2.x)
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from fastmcp.server.providers import MountedProvider
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provider = MountedProvider(server, prefix="api")
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# After (3.x)
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from fastmcp.server.providers import FastMCPProvider
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provider = FastMCPProvider(server).with_namespace("api")
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```
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### prefix → namespace
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```python
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# Before (deprecated)
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main.mount(sub, prefix="api")
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# After
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main.mount(sub, namespace="api")
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```
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## Implementation PRs
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- #2653 - Split MountedProvider into FastMCPProvider + TransformingProvider
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- #2635 - Initial MountedProvider (superseded by #2653)
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