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Remove customizable separators; improve resource separator

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This commit is contained in:
Jeremiah Lowin 2025-05-20 20:30:33 -04:00
commit cec40ddfea
9 changed files with 720 additions and 210 deletions
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44
docs/servers/composition.mdx
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@ -65,7 +65,7 @@ async def setup():
# Result: main_mcp now contains prefixed components:
# - Tool: "weather_get_forecast"
# - Resource: "weather+data://cities/supported"
# - Resource: "data://weather/cities/supported"
if __name__ == "__main__":
asyncio.run(setup())
@ -78,11 +78,11 @@ When you call `await main_mcp.import_server(prefix, subserver)`:
1. **Tools**: All tools from `subserver` are added to `main_mcp` with names prefixed using `{prefix}_`.
- `subserver.tool(name="my_tool")` becomes `main_mcp.tool(name="{prefix}_my_tool")`.
2. **Resources**: All resources are added with URIs prefixed using `{prefix}+`.
- `subserver.resource(uri="data://info")` becomes `main_mcp.resource(uri="{prefix}+data://info")`.
2. **Resources**: All resources are added with URIs prefixed in the format `protocol://{prefix}/path`.
- `subserver.resource(uri="data://info")` becomes `main_mcp.resource(uri="data://{prefix}/info")`.
3. **Resource Templates**: Templates are prefixed similarly to resources.
- `subserver.resource(uri="data://{id}")` becomes `main_mcp.resource(uri="{prefix}+data://{id}")`.
4. **Prompts**: All prompts are added with names prefixed like tools.
- `subserver.resource(uri="data://{id}")` becomes `main_mcp.resource(uri="data://{prefix}/{id}")`.
4. **Prompts**: All prompts are added with names prefixed using `{prefix}_`.
- `subserver.prompt(name="my_prompt")` becomes `main_mcp.prompt(name="{prefix}_my_prompt")`.
Note that `import_server` performs a **one-time copy** of components. Changes made to the `subserver` *after* importing **will not** be reflected in `main_mcp`. The `subserver`'s `lifespan` context is also **not** executed by the main server.
@ -177,36 +177,6 @@ remote_proxy = FastMCP.as_proxy(Client("http://example.com/mcp"))
main_server.mount("remote", remote_proxy)
```
## Customizing Separators
Both `import_server()` and `mount()` allow you to customize the separators used for prefixing components. The defaults are `_` for tools and prompts, and `+` for resources.
<CodeGroup>
```python import_server
await main_mcp.import_server(
prefix="api",
app=some_subserver,
tool_separator="_", # Tool name becomes: "api_sub_tool_name"
resource_separator="+", # Resource URI becomes: "api+data://sub_resource"
prompt_separator="_" # Prompt name becomes: "api_sub_prompt_name"
)
```
```python mount
main_mcp.mount(
prefix="api",
app=some_subserver,
tool_separator="_", # Tool name becomes: "api_sub_tool_name"
resource_separator="+", # Resource URI becomes: "api+data://sub_resource"
prompt_separator="_" # Prompt name becomes: "api_sub_prompt_name"
)
```
</CodeGroup>
<Warning>
Be cautious when choosing separators. Some MCP clients (like Claude Desktop) might have restrictions on characters allowed in tool names (e.g., `/` might not be supported). The defaults (`_` for names, `+` for URIs) are generally safe.
</Warning>
<Tip>
To "cleanly" import or mount a server, set the prefix and all separators to `""` (empty string). This is generally unecessary but could save a couple tokens at the risk of a name collision!
</Tip>
Some MCP clients (like Claude Desktop) might have restrictions on characters allowed in tool names. FastMCP uses standard naming conventions: tools and prompts are prefixed with `{prefix}_` (e.g., "weather_forecast"), and resources use the format `protocol://{prefix}/path` (e.g., "data://weather/forecast").
</Warning>