> ## Documentation Index
> Fetch the complete documentation index at: https://agentheya.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# show_file_excerpt

> Show the content of a public text file inline in the chat.

# show\_file\_excerpt

Shows the content of a public text file inline in the chat bubble. Use when a user asks to see file contents, or when the agent wants to quote a specific section of a document.

Only works for text-based files (`.txt`, `.md`, `.csv`, `.json`, `.yaml`, `.xml`, `.html`, etc.). For binary files, use [present\_public\_file](/builtin-tools/present_public_file) instead.

## Parameters

| Name         | Type         | Required | Description                                                                  |
| ------------ | ------------ | -------- | ---------------------------------------------------------------------------- |
| `filename`   | string       | yes      | Exact filename of the public file to read.                                   |
| `start_line` | integer (≥1) | no       | Line number to start from (1-based). Defaults to 1.                          |
| `end_line`   | integer (≥1) | no       | Line number to end at (inclusive). Defaults to `start_line + 49` (50 lines). |

## Returns

```json theme={null}
{
  "action": "excerpt",
  "filename": "changelog.md",
  "content": "## v2.4.1 — 2026-05-19\n- Fixed CSV export date format\n- ...",
  "totalLines": 312,
  "startLine": 1,
  "endLine": 50
}
```

On failure (file not in manifest, binary extension, or read error):

```json theme={null}
{
  "error": "show_file_excerpt failed: binary file type.",
  "details": {
    "filename": "logo.png",
    "rejection_reason": "binary extension",
    "suggested_tool": "show_image",
    "hint": "Use show_image for .png files."
  }
}
```

***

## Examples

### Show the first 50 lines (default)

```json theme={null}
{ "filename": "faq.md" }
```

### Show a specific section

```json theme={null}
{
  "filename": "changelog.md",
  "start_line": 1,
  "end_line": 30
}
```

### Show a specific CSV section

Show the header row plus rows 1–9 of a CSV:

```json theme={null}
{
  "filename": "orders.csv",
  "start_line": 1,
  "end_line": 10
}
```

### Page through a large file (custom tool)

```js theme={null}
export async function handle(input, ctx) {
  const pageSize  = 50;
  const page      = input.page ?? 1;
  const startLine = (page - 1) * pageSize + 1;
  const endLine   = page * pageSize;

  const result = await ctx.tools.show_file_excerpt({
    filename:   input.filename,
    start_line: startLine,
    end_line:   endLine,
  });

  return {
    page,
    total_lines: result.totalLines,
    total_pages: Math.ceil(result.totalLines / pageSize),
    content:     result.content,
  };
}
```

***

## Call from your own custom tool

```js theme={null}
export async function handle(input, ctx) {
  return await ctx.tools.show_file_excerpt({
    filename:   input.doc,
    start_line: input.from_line ?? 1,
    end_line:   input.to_line,
  });
}
```

```python theme={null}
async def handle(input, ctx):
    return await ctx.tools.show_file_excerpt({
        'filename':   input['doc'],
        'start_line': input.get('from_line', 1),
        'end_line':   input.get('to_line'),
    })
```

## Notes

* Only registered when the agent has public files.
* Binary extensions (`.pdf`, `.png`, `.jpg`, `.docx`, `.xlsx`, archives, etc.) are rejected with a `suggested_tool` hint.
* To offer the full file as a download instead of showing it inline, use [present\_public\_file](/builtin-tools/present_public_file).