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293 lines
10 KiB
Text
293 lines
10 KiB
Text
---
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title: context
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sidebarTitle: context
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---
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# `fastmcp.server.context`
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## Functions
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### `set_context` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L50" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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set_context(context: Context) -> Generator[Context, None, None]
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```
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## Classes
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### `Context` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L59" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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Context object providing access to MCP capabilities.
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This provides a cleaner interface to MCP's RequestContext functionality.
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It gets injected into tool and resource functions that request it via type hints.
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To use context in a tool function, add a parameter with the Context type annotation:
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```python
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@server.tool
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def my_tool(x: int, ctx: Context) -> str:
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# Log messages to the client
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ctx.info(f"Processing {x}")
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ctx.debug("Debug info")
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ctx.warning("Warning message")
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ctx.error("Error message")
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# Report progress
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ctx.report_progress(50, 100, "Processing")
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# Access resources
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data = ctx.read_resource("resource://data")
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# Get request info
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request_id = ctx.request_id
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client_id = ctx.client_id
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return str(x)
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```
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The context parameter name can be anything as long as it's annotated with Context.
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The context is optional - tools that don't need it can omit the parameter.
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**Methods:**
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#### `request_context` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L116" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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request_context(self) -> RequestContext
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```
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Access to the underlying request context.
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If called outside of a request context, this will raise a ValueError.
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#### `report_progress` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L126" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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report_progress(self, progress: float, total: float | None = None, message: str | None = None) -> None
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```
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Report progress for the current operation.
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**Args:**
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- `progress`: Current progress value e.g. 24
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- `total`: Optional total value e.g. 100
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#### `read_resource` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L153" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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read_resource(self, uri: str | AnyUrl) -> list[ReadResourceContents]
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```
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Read a resource by URI.
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**Args:**
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- `uri`: Resource URI to read
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**Returns:**
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- The resource content as either text or bytes
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#### `log` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L165" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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log(self, message: str, level: LoggingLevel | None = None, logger_name: str | None = None) -> None
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```
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Send a log message to the client.
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**Args:**
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- `message`: Log message
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- `level`: Optional log level. One of "debug", "info", "notice", "warning", "error", "critical",
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"alert", or "emergency". Default is "info".
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- `logger_name`: Optional logger name
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#### `client_id` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L189" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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client_id(self) -> str | None
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```
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Get the client ID if available.
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#### `request_id` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L198" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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request_id(self) -> str
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```
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Get the unique ID for this request.
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#### `session_id` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L203" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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session_id(self) -> str | None
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```
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Get the MCP session ID for HTTP transports.
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Returns the session ID that can be used as a key for session-based
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data storage (e.g., Redis) to share data between tool calls within
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the same client session.
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**Returns:**
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- The session ID for HTTP transports (SSE, StreamableHTTP), or None
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- for stdio and in-memory transports which don't use session IDs.
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#### `session` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L234" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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session(self) -> ServerSession
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```
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Access to the underlying session for advanced usage.
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#### `debug` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L239" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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debug(self, message: str, logger_name: str | None = None) -> None
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```
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Send a debug log message.
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#### `info` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L243" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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info(self, message: str, logger_name: str | None = None) -> None
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```
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Send an info log message.
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#### `warning` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L247" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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warning(self, message: str, logger_name: str | None = None) -> None
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```
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Send a warning log message.
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#### `error` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L251" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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error(self, message: str, logger_name: str | None = None) -> None
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```
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Send an error log message.
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#### `list_roots` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L255" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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list_roots(self) -> list[Root]
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```
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List the roots available to the server, as indicated by the client.
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#### `send_tool_list_changed` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L260" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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send_tool_list_changed(self) -> None
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```
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Send a tool list changed notification to the client.
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#### `send_resource_list_changed` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L264" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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send_resource_list_changed(self) -> None
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```
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Send a resource list changed notification to the client.
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#### `send_prompt_list_changed` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L268" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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send_prompt_list_changed(self) -> None
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```
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Send a prompt list changed notification to the client.
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#### `sample` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L272" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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sample(self, messages: str | list[str | SamplingMessage], system_prompt: str | None = None, include_context: IncludeContext | None = None, temperature: float | None = None, max_tokens: int | None = None, model_preferences: ModelPreferences | str | list[str] | None = None) -> ContentBlock
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```
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Send a sampling request to the client and await the response.
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Call this method at any time to have the server request an LLM
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completion from the client. The client must be appropriately configured,
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or the request will error.
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#### `elicit` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L319" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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elicit(self, message: str, response_type: None) -> AcceptedElicitation[dict[str, Any]] | DeclinedElicitation | CancelledElicitation
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```
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#### `elicit` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L331" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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elicit(self, message: str, response_type: type[T]) -> AcceptedElicitation[T] | DeclinedElicitation | CancelledElicitation
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```
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#### `elicit` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L341" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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elicit(self, message: str, response_type: list[str]) -> AcceptedElicitation[str] | DeclinedElicitation | CancelledElicitation
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```
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#### `elicit` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L350" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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elicit(self, message: str, response_type: type[T] | list[str] | None = None) -> AcceptedElicitation[T] | AcceptedElicitation[dict[str, Any]] | AcceptedElicitation[str] | DeclinedElicitation | CancelledElicitation
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```
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Send an elicitation request to the client and await the response.
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Call this method at any time to request additional information from
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the user through the client. The client must support elicitation,
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or the request will error.
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Note that the MCP protocol only supports simple object schemas with
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primitive types. You can provide a dataclass, TypedDict, or BaseModel to
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comply. If you provide a primitive type, an object schema with a single
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"value" field will be generated for the MCP interaction and
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automatically deconstructed into the primitive type upon response.
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If the response_type is None, the generated schema will be that of an
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empty object in order to comply with the MCP protocol requirements.
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Clients must send an empty object ("{}")in response.
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**Args:**
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- `message`: A human-readable message explaining what information is needed
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- `response_type`: The type of the response, which should be a primitive
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type or dataclass or BaseModel. If it is a primitive type, an
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object schema with a single "value" field will be generated.
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#### `get_http_request` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/context.py#L443" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
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```python
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get_http_request(self) -> Request
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```
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Get the active starlette request.
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