feat: add ReadFileTool for agent file access

- Create read_file tool for agents to access attached files
- Support reading by file name from crew/task file store
- Add unit tests for ReadFileTool

lib/crewai/src/crewai/tools/agent_tools/read_file_tool.py

@@ -0,0 +1,80 @@
+"""Tool for reading input files provided to the crew."""
+
+from __future__ import annotations
+
+import base64
+from typing import TYPE_CHECKING
+
+from pydantic import BaseModel, Field, PrivateAttr
+
+from crewai.tools.base_tool import BaseTool
+
+
+if TYPE_CHECKING:
+    from crewai.utilities.files import FileInput
+
+
+class ReadFileToolSchema(BaseModel):
+    """Schema for read file tool arguments."""
+
+    file_name: str = Field(..., description="The name of the input file to read")
+
+
+class ReadFileTool(BaseTool):
+    """Tool for reading input files provided to the crew kickoff.
+
+    Provides agents access to files passed via the `files` key in inputs.
+    """
+
+    name: str = "read_file"
+    description: str = (
+        "Read content from an input file by name. "
+        "Returns file content as text for text files, or base64 for binary files."
+    )
+    args_schema: type[BaseModel] = ReadFileToolSchema
+
+    _files: dict[str, FileInput] | None = PrivateAttr(default=None)
+
+    def set_files(self, files: dict[str, FileInput] | None) -> None:
+        """Set available input files.
+
+        Args:
+            files: Dictionary mapping file names to file inputs.
+        """
+        self._files = files
+
+    def _run(self, file_name: str, **kwargs: object) -> str:
+        """Read an input file by name.
+
+        Args:
+            file_name: The name of the file to read.
+
+        Returns:
+            File content as text for text files, or base64 encoded for binary.
+        """
+        if not self._files:
+            return "No input files available."
+
+        if file_name not in self._files:
+            available = ", ".join(self._files.keys())
+            return f"File '{file_name}' not found. Available files: {available}"
+
+        file_input = self._files[file_name]
+        content = file_input.read()
+        content_type = file_input.content_type
+        filename = file_input.filename or file_name
+
+        # Text-based content types
+        text_types = (
+            "text/",
+            "application/json",
+            "application/xml",
+            "application/x-yaml",
+        )
+
+        if any(content_type.startswith(t) for t in text_types):
+            return content.decode("utf-8")
+
+        # Binary content - return base64 encoded
+        encoded = base64.b64encode(content).decode("ascii")
+        return f"[Binary file: {filename} ({content_type})]\nBase64: {encoded}"

lib/crewai/tests/tools/agent_tools/test_read_file_tool.py

@@ -0,0 +1,122 @@
+"""Unit tests for ReadFileTool."""
+
+import base64
+
+import pytest
+
+from crewai.tools.agent_tools.read_file_tool import ReadFileTool
+from crewai.utilities.files import ImageFile, PDFFile, TextFile
+
+
+class TestReadFileTool:
+    """Tests for ReadFileTool."""
+
+    def setup_method(self) -> None:
+        """Set up test fixtures."""
+        self.tool = ReadFileTool()
+
+    def test_tool_metadata(self) -> None:
+        """Test tool has correct name and description."""
+        assert self.tool.name == "read_file"
+        assert "Read content from an input file" in self.tool.description
+
+    def test_run_no_files_available(self) -> None:
+        """Test _run returns message when no files are set."""
+        result = self.tool._run(file_name="any.txt")
+        assert result == "No input files available."
+
+    def test_run_file_not_found(self) -> None:
+        """Test _run returns message when file not found."""
+        self.tool.set_files({"doc.txt": TextFile(source=b"content")})
+
+        result = self.tool._run(file_name="missing.txt")
+
+        assert "File 'missing.txt' not found" in result
+        assert "doc.txt" in result  # Lists available files
+
+    def test_run_text_file(self) -> None:
+        """Test reading a text file returns decoded content."""
+        text_content = "Hello, this is text content!"
+        self.tool.set_files({"readme.txt": TextFile(source=text_content.encode())})
+
+        result = self.tool._run(file_name="readme.txt")
+
+        assert result == text_content
+
+    def test_run_json_file(self) -> None:
+        """Test reading a JSON file returns decoded content."""
+        json_content = '{"key": "value"}'
+        self.tool.set_files({"data.json": TextFile(source=json_content.encode())})
+
+        result = self.tool._run(file_name="data.json")
+
+        assert result == json_content
+
+    def test_run_binary_file_returns_base64(self) -> None:
+        """Test reading a binary file returns base64 encoded content."""
+        # Minimal valid PNG structure for proper MIME detection
+        png_bytes = (
+            b"\x89PNG\r\n\x1a\n"
+            b"\x00\x00\x00\rIHDR"
+            b"\x00\x00\x00\x01\x00\x00\x00\x01\x08\x02\x00\x00\x00"
+            b"\x90wS\xde"
+            b"\x00\x00\x00\x00IEND\xaeB`\x82"
+        )
+        self.tool.set_files({"image.png": ImageFile(source=png_bytes)})
+
+        result = self.tool._run(file_name="image.png")
+
+        assert "[Binary file:" in result
+        assert "image/png" in result
+        assert "Base64:" in result
+
+        # Verify base64 can be decoded
+        b64_part = result.split("Base64: ")[1]
+        decoded = base64.b64decode(b64_part)
+        assert decoded == png_bytes
+
+    def test_run_pdf_file_returns_base64(self) -> None:
+        """Test reading a PDF file returns base64 encoded content."""
+        pdf_bytes = b"%PDF-1.4 some content here"
+        self.tool.set_files({"doc.pdf": PDFFile(source=pdf_bytes)})
+
+        result = self.tool._run(file_name="doc.pdf")
+
+        assert "[Binary file:" in result
+        assert "application/pdf" in result
+
+    def test_set_files_none(self) -> None:
+        """Test setting files to None."""
+        self.tool.set_files({"doc": TextFile(source=b"content")})
+        self.tool.set_files(None)
+
+        result = self.tool._run(file_name="doc")
+
+        assert result == "No input files available."
+
+    def test_run_multiple_files(self) -> None:
+        """Test tool can access multiple files."""
+        self.tool.set_files({
+            "file1.txt": TextFile(source=b"content 1"),
+            "file2.txt": TextFile(source=b"content 2"),
+            "file3.txt": TextFile(source=b"content 3"),
+        })
+
+        assert self.tool._run(file_name="file1.txt") == "content 1"
+        assert self.tool._run(file_name="file2.txt") == "content 2"
+        assert self.tool._run(file_name="file3.txt") == "content 3"
+
+    def test_run_with_kwargs(self) -> None:
+        """Test _run ignores extra kwargs."""
+        self.tool.set_files({"doc.txt": TextFile(source=b"content")})
+
+        result = self.tool._run(file_name="doc.txt", extra_arg="ignored")
+
+        assert result == "content"
+
+    def test_args_schema(self) -> None:
+        """Test that args_schema is properly defined."""
+        schema = self.tool.args_schema
+
+        assert "file_name" in schema.model_fields
+        assert schema.model_fields["file_name"].is_required()