"""Add a new tool to an existing scaffolded MCP server project."""
from __future__ import annotations
import json
from pathlib import Path
from mcp_creator.services import codegen, file_writer
def add_tool(project_dir: str, tool: str) -> str:
"""Add a new tool to an existing scaffolded MCP server.
Args:
project_dir: Absolute path to the project root.
tool: JSON string — a single tool definition:
{"name": "get_forecast", "description": "...",
"parameters": [...], "returns": "..."}
Returns:
JSON string with created/modified files and next steps.
"""
tool_def = json.loads(tool)
tool_name = tool_def["name"]
project = Path(project_dir).resolve()
# Detect module name from the src/ directory
src_dir = project / "src"
if not src_dir.exists():
return json.dumps({
"success": False,
"error": f"No src/ directory found at {project}. Is this a scaffolded MCP project?",
})
module_dirs = [d for d in src_dir.iterdir() if d.is_dir() and not d.name.startswith("_")]
if not module_dirs:
return json.dumps({
"success": False,
"error": "No module directory found under src/.",
})
module_name = module_dirs[0].name
package_name = module_name.replace("_", "-")
# 1. Create tool module
tool_file = f"src/{module_name}/tools/{tool_name}.py"
tool_content = codegen.render_tool_module(package_name, tool_def)
# 2. Create service stub
service_file = f"src/{module_name}/services/{tool_name}_service.py"
service_content = codegen.render_service_module(tool_def)
# 3. Create test
test_file = f"tests/test_{tool_name}.py"
test_content = codegen.render_test_tool(package_name, tool_def)
files_to_write = {
tool_file: tool_content,
service_file: service_content,
test_file: test_content,
}
written = file_writer.write_project_files(project, files_to_write)
# 4. Inject import into server.py
server_path = project / f"src/{module_name}/server.py"
import_line = codegen.render_add_tool_import(package_name, tool_name)
import_ok = file_writer.inject_after_sentinel(
server_path, "# --- IMPORTS ---", import_line
)
# 5. Inject tool registration into server.py
registration = codegen.render_add_tool_registration(tool_def)
reg_ok = file_writer.inject_after_sentinel(
server_path, "# --- END TOOLS ---", ""
)
# Actually inject before END TOOLS
reg_ok = file_writer.inject_after_sentinel(
server_path, "# --- TOOLS ---", registration
)
result = {
"success": True,
"tool_name": tool_name,
"files_created": [tool_file, service_file, test_file],
"server_updated": import_ok and reg_ok,
"next_steps": [
f"Tool '{tool_name}' added to the project.",
f"Implement your logic in src/{module_name}/services/{tool_name}_service.py",
"Run 'pytest -v' to verify it registers correctly.",
],
}
return json.dumps(result, indent=2)
