> ## Documentation Index
> Fetch the complete documentation index at: https://mcp-use.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
## Submitting Feedback
If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:
POST https://mcp-use.com/docs/feedback
```json
{
"path": "/python/api-reference/mcp_use_agents_prompts_system_prompt_builder",
"feedback": "Description of the issue"
}
```
Only submit feedback when you have something specific and actionable to report.
# System Prompt Builder
> System Prompt Builder API Documentation
export const RandomGradientBackground = ({className, color, children, grayscaled = false}) => {
const saturation = useMemo(() => {
if (color) {
const values = color.split("(")[1].split(")")[0].trim().split(/\s+/);
return parseFloat(values[1] || "0");
}
return grayscaled ? 0 : 0.2;
}, [color, grayscaled]);
const lightness = useMemo(() => {
if (color) {
const values = color.split("(")[1].split(")")[0].trim().split(/\s+/);
return parseFloat(values[0] || "0.5");
}
return grayscaled ? 0.3 : 0.4;
}, [color, grayscaled]);
const randomHue = useMemo(() => {
if (color) {
const values = color.split("(")[1].split(")")[0].trim().split(/\s+/);
return parseFloat(values[2] || "0");
}
return Math.floor(Math.random() * 360);
}, [color]);
const randomColor = useMemo(() => {
if (color) {
return color;
}
return `oklch(${Math.min(lightness, 1)} ${saturation} ${randomHue})`;
}, [randomHue, saturation, lightness]);
const lightColor = useMemo(() => {
return `oklch(${Math.min(lightness * 2, 1)} ${saturation} ${randomHue})`;
}, [randomHue, saturation, lightness, color]);
const direction = useMemo(() => {
return Math.floor(Math.random() * 360);
}, [randomHue]);
const brightnessFilter = useMemo(() => {
return "1000%";
}, []);
return ;
};
View the source code for this module on GitHub: [https://github.com/mcp-use/mcp-use/blob/main/libraries/python/mcp\_use/agents/prompts/system\_prompt\_builder.py](https://github.com/mcp-use/mcp-use/blob/main/libraries/python/mcp_use/agents/prompts/system_prompt_builder.py)
## build\_system\_prompt\_content
### `function` build\_system\_prompt\_content
Builds the final system prompt string using a template, tool descriptions,
and optional additional instructions.
```python theme={null}
from mcp_use.agents.prompts.system_prompt_builder import build_system_prompt_content
```
**Parameters**
> The system prompt template string (must contain '{tool_descriptions}').
> A list of formatted tool description strings.
> Optional extra instructions to append.
**Returns**
> The fully formatted system prompt content string.
**Signature**
```python wrap theme={null}
def build_system_prompt_content(
template: str,
tool_description_lines: list[str],
additional_instructions: str | None = None
):
```
## create\_system\_message
### `function` create\_system\_message
Creates the final SystemMessage object for the agent.
Handles selecting the correct template, generating tool descriptions,
and incorporating user overrides and additional instructions.
```python theme={null}
from mcp_use.agents.prompts.system_prompt_builder import create_system_message
```
**Parameters**
> List of available tools.
> The default system prompt template.
> The template to use when server manager is active.
> Flag indicating if server manager mode is enabled.
> List of tool names to exclude.
> A complete system prompt provided by the user, overriding templates.
> Extra instructions to append to the template-based prompt.
**Returns**
> A SystemMessage object containing the final prompt content.
**Signature**
```python wrap theme={null}
def create_system_message(
tools: list[langchain_core.tools.base.BaseTool],
system_prompt_template: str,
server_manager_template: str,
use_server_manager: bool,
disallowed_tools: list[str] | None = None,
user_provided_prompt: str | None = None,
additional_instructions: str | None = None
):
```
## generate\_tool\_descriptions
### `function` generate\_tool\_descriptions
Generates a list of formatted tool descriptions, excluding disallowed tools.
```python theme={null}
from mcp_use.agents.prompts.system_prompt_builder import generate_tool_descriptions
```
**Parameters**
> The list of available BaseTool objects.
> A list of tool names to exclude.
**Returns**
> A list of strings, each describing a tool in the format "- tool\_name: description".
**Signature**
```python wrap theme={null}
def generate_tool_descriptions(
tools: list[langchain_core.tools.base.BaseTool],
disallowed_tools: list[str] | None = None
):
```