file_read
Read the contents of a file. Supports reading specific line ranges.
Parameters
| Parameter | Type | Required | Description |
|---|
path | string | Yes | Path to the file (relative to working directory) |
offset | integer | No | Line number to start reading from (0-based) |
limit | integer | No | Maximum number of lines to read |
Example
Reading a file with a line range:
{
"path": "src/main.rs",
"offset": 10,
"limit": 20
}
src/main.rs.
file_write
Create or overwrite a file. Automatically creates parent directories if they do not exist.
Parameters
| Parameter | Type | Required | Description |
|---|
path | string | Yes | Path to the file |
content | string | Yes | Content to write |
Example
{
"path": "src/utils.rs",
"content": "pub fn add(a: i32, b: i32) -> i32 {\n a + b\n}\n"
}
file_write overwrites the entire file. For targeted edits, use file_edit or apply_patch instead.
file_edit
Edit a file by replacing an exact string match. The old_string must match exactly once in the file.
Parameters
| Parameter | Type | Required | Description |
|---|
path | string | Yes | Path to the file |
old_string | string | Yes | Exact text to find (must be unique in the file) |
new_string | string | Yes | Replacement text |
Example
{
"path": "src/main.rs",
"old_string": "fn main() {\n println!(\"Hello\");\n}",
"new_string": "fn main() {\n println!(\"Hello, world!\");\n}"
}
old_string matches multiple locations or is not found, the edit fails with an error.
apply_patch
Apply a unified diff patch. Supports Claude Code-style patch format with fuzzy matching for context lines.
*** Begin Patch
*** Add File: path/to/new_file.rs
+line 1
+line 2
*** Update File: path/to/existing.rs
context line
-old line
+new line
context line
*** Delete File: path/to/old_file.rs
*** End Patch
Patch Sections
| Section | Description |
|---|
*** Add File | Create a new file with the specified content |
*** Update File | Modify an existing file using diff hunks |
*** Delete File | Remove a file |
Fuzzy Matching
When applying updates, the patch tool uses fuzzy matching for context lines. If the exact context is not found, it searches within a 3-line window to find the best match. This makes patches more resilient to minor whitespace or formatting differences.
Example
*** Begin Patch
*** Update File: src/lib.rs
use std::io;
-pub fn read_input() -> String {
+pub fn read_input() -> Result<String, io::Error> {
let mut input = String::new();
- std::io::stdin().read_line(&mut input).unwrap();
- input
+ std::io::stdin().read_line(&mut input)?;
+ Ok(input)
}
*** End Patch