truncate()

Truncates text content in tool responses.

Import

import { truncate } from "@lynq/lynq/truncate";

Usage

server.tool("search", truncate({ maxChars: 1000 }), config, handler);

Options

Option	Type	Default	Description
maxChars	number	(required)	Maximum characters per text block
suffix	string	"..."	Appended to truncated text

Example

import { createMCPServer, text } from "@lynq/lynq";
import { truncate } from "@lynq/lynq/truncate";

const server = createMCPServer({ name: "my-app", version: "1.0.0" });

server.tool(
  "search",
  truncate({ maxChars: 500 }),
  { description: "Search documents" },
  async (c) => {
    const doc = await documents.find(c.params.query);
    return text(doc.fullText); // may be thousands of chars
  },
);

If doc.fullText is 2000 characters, the response is trimmed to 497 characters plus "..." (500 total). A custom suffix can be specified:

truncate({ maxChars: 500, suffix: " [truncated]" })

Under the hood

Uses the onResult hook, which runs after the handler returns. Iterates over result.content and truncates only blocks with type: "text". Other content types (images, embedded resources, etc.) pass through unchanged. The suffix length is subtracted from maxChars so the total output never exceeds the limit.