---
title: base
sidebarTitle: base
---

# `fastmcp.prompts.base`


Base classes for FastMCP prompts.

## Classes

### `Message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L44" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Wrapper for prompt message with auto-serialization.

Accepts any content - strings pass through, other types
(dict, list, BaseModel) are JSON-serialized to text.


**Methods:**

#### `to_mcp_prompt_message` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L99" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_mcp_prompt_message(self) -> PromptMessage
```

Convert to MCP PromptMessage.


### `PromptArgument` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L104" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


An argument that can be passed to a prompt.


### `PromptResult` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L116" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Canonical result type for prompt rendering.

Provides explicit control over prompt responses: multiple messages,
roles, and metadata at both the message and result level.


**Methods:**

#### `to_mcp_prompt_result` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L188" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_mcp_prompt_result(self) -> GetPromptResult
```

Convert to MCP GetPromptResult.


### `Prompt` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L198" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


A prompt template that can be rendered with parameters.


**Methods:**

#### `to_mcp_prompt` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L210" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
to_mcp_prompt(self, **overrides: Any) -> SDKPrompt
```

Convert the prompt to an MCP prompt.


#### `from_function` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L236" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_function(cls, fn: Callable[..., Any]) -> FunctionPrompt
```

Create a Prompt from a function.

The function can return:
- str: wrapped as single user Message
- list\[Message | str]: converted to list\[Message]
- PromptResult: used directly


#### `render` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L272" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
render(self, arguments: dict[str, Any] | None = None) -> str | list[Message | str] | PromptResult
```

Render the prompt with arguments.

Subclasses must implement this method. Return one of:
- str: Wrapped as single user Message
- list\[Message | str]: Converted to list\[Message]
- PromptResult: Used directly


#### `convert_result` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L285" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
convert_result(self, raw_value: Any) -> PromptResult
```

Convert a raw return value to PromptResult.

**Raises:**
- `TypeError`: for unsupported types


#### `register_with_docket` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L375" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
register_with_docket(self, docket: Docket) -> None
```

Register this prompt with docket for background execution.


#### `add_to_docket` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L381" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
add_to_docket(self, docket: Docket, arguments: dict[str, Any] | None, **kwargs: Any) -> Execution
```

Schedule this prompt for background execution via docket.

**Args:**
- `docket`: The Docket instance
- `arguments`: Prompt arguments
- `fn_key`: Function lookup key in Docket registry (defaults to self.key)
- `task_key`: Redis storage key for the result
- `**kwargs`: Additional kwargs passed to docket.add()


#### `get_span_attributes` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/prompts/base.py#L404" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_span_attributes(self) -> dict[str, Any]
```
