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/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import path from 'path';
import { SchemaValidator } from '../utils/schemaValidator.js';
import { makeRelative, shortenPath } from '../utils/paths.js';
import { BaseTool, ToolResult } from './tools.js';
import { isWithinRoot, processSingleFileContent } from '../utils/fileUtils.js';
/**
* Parameters for the ReadFile tool
*/
export interface ReadFileToolParams {
/**
* The absolute path to the file to read
*/
path: string;
/**
* The line number to start reading from (optional)
*/
offset?: number;
/**
* The number of lines to read (optional)
*/
limit?: number;
}
/**
* Implementation of the ReadFile tool logic
*/
export class ReadFileTool extends BaseTool<ReadFileToolParams, ToolResult> {
static readonly Name: string = 'read_file';
constructor(private rootDirectory: string) {
super(
ReadFileTool.Name,
'ReadFile',
'Reads and returns the content of a specified file from the local filesystem. Handles text, images (PNG, JPG, GIF, WEBP, SVG, BMP), and PDF files. For text files, it can read specific line ranges.',
{
properties: {
path: {
description:
"The absolute path to the file to read (e.g., '/home/user/project/file.txt'). Relative paths are not supported.",
type: 'string',
},
offset: {
description:
"Optional: For text files, the 0-based line number to start reading from. Requires 'limit' to be set. Use for paginating through large files.",
type: 'number',
},
limit: {
description:
"Optional: For text files, maximum number of lines to read. Use with 'offset' to paginate through large files. If omitted, reads the entire file (if feasible, up to a default limit).",
type: 'number',
},
},
required: ['path'],
type: 'object',
},
);
this.rootDirectory = path.resolve(rootDirectory);
}
validateToolParams(params: ReadFileToolParams): string | null {
if (
this.schema.parameters &&
!SchemaValidator.validate(
this.schema.parameters as Record<string, unknown>,
params,
)
) {
return 'Parameters failed schema validation.';
}
const filePath = params.path;
if (!path.isAbsolute(filePath)) {
return `File path must be absolute: ${filePath}`;
}
if (!isWithinRoot(filePath, this.rootDirectory)) {
return `File path must be within the root directory (${this.rootDirectory}): ${filePath}`;
}
if (params.offset !== undefined && params.offset < 0) {
return 'Offset must be a non-negative number';
}
if (params.limit !== undefined && params.limit <= 0) {
return 'Limit must be a positive number';
}
return null;
}
getDescription(params: ReadFileToolParams): string {
const relativePath = makeRelative(params.path, this.rootDirectory);
return shortenPath(relativePath);
}
async execute(
params: ReadFileToolParams,
_signal: AbortSignal,
): Promise<ToolResult> {
const validationError = this.validateToolParams(params);
if (validationError) {
return {
llmContent: `Error: Invalid parameters provided. Reason: ${validationError}`,
returnDisplay: validationError,
};
}
const result = await processSingleFileContent(
params.path,
this.rootDirectory,
params.offset,
params.limit,
);
if (result.error) {
return {
llmContent: result.error, // The detailed error for LLM
returnDisplay: result.returnDisplay, // User-friendly error
};
}
return {
llmContent: result.llmContent,
returnDisplay: result.returnDisplay,
};
}
}
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