mcp-use/dist/src/agents/prompts/system_prompt_builder.js

A utility library for integrating Model Context Protocol (MCP) with LangChain, Zod, and related tools. Provides helpers for schema conversion, event streaming, and SDK usage.

import { SystemMessage } from '@langchain/core/messages';
export function generateToolDescriptions(tools, disallowedTools) {
    const disallowedSet = new Set(disallowedTools ?? []);
    const descriptions = [];
    for (const tool of tools) {
        if (disallowedSet.has(tool.name))
            continue;
        const escaped = tool.description
            .replace(/\{/g, '{{')
            .replace(/\}/g, '}}');
        descriptions.push(`- ${tool.name}: ${escaped}`);
    }
    return descriptions;
}
export function buildSystemPromptContent(template, toolDescriptionLines, additionalInstructions) {
    const block = toolDescriptionLines.join('\n');
    let content;
    if (template.includes('{tool_descriptions}')) {
        content = template.replace('{tool_descriptions}', block);
    }
    else {
        console.warn('`{tool_descriptions}` placeholder not found; appending at end.');
        content = `${template}\n\nAvailable tools:\n${block}`;
    }
    if (additionalInstructions) {
        content += `\n\n${additionalInstructions}`;
    }
    return content;
}
export function createSystemMessage(tools, systemPromptTemplate, serverManagerTemplate, useServerManager, disallowedTools, userProvidedPrompt, additionalInstructions) {
    if (userProvidedPrompt) {
        return new SystemMessage({ content: userProvidedPrompt });
    }
    const template = useServerManager
        ? serverManagerTemplate
        : systemPromptTemplate;
    const toolLines = generateToolDescriptions(tools, disallowedTools);
    const finalContent = buildSystemPromptContent(template, toolLines, additionalInstructions);
    return new SystemMessage({ content: finalContent });
}