285 lines
9.3 KiB
Python
Executable File
285 lines
9.3 KiB
Python
Executable File
#!/usr/bin/env python3
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"""Generate MCP scaffold files from an OpenAPI specification.
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Input sources:
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- --input <file>
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- stdin (JSON or YAML when PyYAML is available)
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Output:
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- tool_manifest.json
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- server.py or server.ts scaffold
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- summary in text/json
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"""
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import argparse
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import json
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import re
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import sys
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from dataclasses import dataclass, asdict
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from pathlib import Path
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from typing import Any, Dict, List, Optional
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HTTP_METHODS = {"get", "post", "put", "patch", "delete"}
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class CLIError(Exception):
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"""Raised for expected CLI failures."""
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@dataclass
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class GenerationSummary:
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server_name: str
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language: str
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operations_total: int
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tools_generated: int
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output_dir: str
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manifest_path: str
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scaffold_path: str
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def parse_args() -> argparse.Namespace:
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parser = argparse.ArgumentParser(description="Generate MCP server scaffold from OpenAPI.")
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parser.add_argument("--input", help="OpenAPI file path (JSON or YAML). If omitted, reads from stdin.")
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parser.add_argument("--server-name", required=True, help="MCP server name.")
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parser.add_argument("--language", choices=["python", "typescript"], default="python", help="Scaffold language.")
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parser.add_argument("--output-dir", default=".", help="Directory to write generated files.")
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parser.add_argument("--format", choices=["text", "json"], default="text", help="Output format.")
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return parser.parse_args()
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def load_raw_input(input_path: Optional[str]) -> str:
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if input_path:
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try:
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return Path(input_path).read_text(encoding="utf-8")
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except Exception as exc:
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raise CLIError(f"Failed to read --input file: {exc}") from exc
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if sys.stdin.isatty():
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raise CLIError("No input provided. Use --input <spec-file> or pipe OpenAPI via stdin.")
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data = sys.stdin.read().strip()
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if not data:
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raise CLIError("Stdin was provided but empty.")
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return data
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def parse_openapi(raw: str) -> Dict[str, Any]:
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try:
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return json.loads(raw)
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except json.JSONDecodeError:
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try:
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import yaml # type: ignore
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parsed = yaml.safe_load(raw)
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if not isinstance(parsed, dict):
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raise CLIError("YAML OpenAPI did not parse into an object.")
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return parsed
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except ImportError as exc:
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raise CLIError("Input is not valid JSON and PyYAML is unavailable for YAML parsing.") from exc
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except Exception as exc:
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raise CLIError(f"Failed to parse OpenAPI input: {exc}") from exc
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def sanitize_tool_name(name: str) -> str:
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cleaned = re.sub(r"[^a-zA-Z0-9_]+", "_", name).strip("_")
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cleaned = re.sub(r"_+", "_", cleaned)
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return cleaned.lower() or "unnamed_tool"
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def schema_from_parameter(param: Dict[str, Any]) -> Dict[str, Any]:
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schema = param.get("schema", {})
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if not isinstance(schema, dict):
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schema = {}
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out = {
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"type": schema.get("type", "string"),
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"description": param.get("description", ""),
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}
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if "enum" in schema:
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out["enum"] = schema["enum"]
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return out
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def extract_tools(spec: Dict[str, Any]) -> List[Dict[str, Any]]:
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paths = spec.get("paths", {})
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if not isinstance(paths, dict):
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raise CLIError("OpenAPI spec missing valid 'paths' object.")
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tools = []
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for path, methods in paths.items():
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if not isinstance(methods, dict):
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continue
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for method, operation in methods.items():
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method_l = str(method).lower()
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if method_l not in HTTP_METHODS or not isinstance(operation, dict):
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continue
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op_id = operation.get("operationId")
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if op_id:
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name = sanitize_tool_name(str(op_id))
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else:
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name = sanitize_tool_name(f"{method_l}_{path}")
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description = str(operation.get("summary") or operation.get("description") or f"{method_l.upper()} {path}")
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properties: Dict[str, Any] = {}
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required: List[str] = []
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for param in operation.get("parameters", []):
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if not isinstance(param, dict):
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continue
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pname = str(param.get("name", "")).strip()
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if not pname:
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continue
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properties[pname] = schema_from_parameter(param)
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if bool(param.get("required")):
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required.append(pname)
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request_body = operation.get("requestBody", {})
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if isinstance(request_body, dict):
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content = request_body.get("content", {})
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if isinstance(content, dict):
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app_json = content.get("application/json", {})
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if isinstance(app_json, dict):
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schema = app_json.get("schema", {})
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if isinstance(schema, dict) and schema.get("type") == "object":
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rb_props = schema.get("properties", {})
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if isinstance(rb_props, dict):
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for key, val in rb_props.items():
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if isinstance(val, dict):
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properties[key] = val
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rb_required = schema.get("required", [])
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if isinstance(rb_required, list):
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required.extend([str(x) for x in rb_required])
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tool = {
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"name": name,
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"description": description,
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"inputSchema": {
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"type": "object",
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"properties": properties,
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"required": sorted(set(required)),
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},
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"x-openapi": {"path": path, "method": method_l},
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}
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tools.append(tool)
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return tools
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def python_scaffold(server_name: str, tools: List[Dict[str, Any]]) -> str:
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handlers = []
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for tool in tools:
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fname = sanitize_tool_name(tool["name"])
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handlers.append(
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f"@mcp.tool()\ndef {fname}(input: dict) -> dict:\n"
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f" \"\"\"{tool['description']}\"\"\"\n"
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f" return {{\"tool\": \"{tool['name']}\", \"status\": \"todo\", \"input\": input}}\n"
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)
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return "\n".join(
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[
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"#!/usr/bin/env python3",
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'"""Generated MCP server scaffold."""',
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"",
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"from fastmcp import FastMCP",
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"",
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f"mcp = FastMCP(name={server_name!r})",
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"",
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*handlers,
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"",
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"if __name__ == '__main__':",
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" mcp.run()",
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"",
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]
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)
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def typescript_scaffold(server_name: str, tools: List[Dict[str, Any]]) -> str:
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registrations = []
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for tool in tools:
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const_name = sanitize_tool_name(tool["name"])
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registrations.append(
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"server.tool(\n"
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f" '{tool['name']}',\n"
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f" '{tool['description']}',\n"
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" async (input) => ({\n"
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f" content: [{{ type: 'text', text: JSON.stringify({{ tool: '{const_name}', status: 'todo', input }}) }}],\n"
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" })\n"
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");"
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)
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return "\n".join(
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[
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"// Generated MCP server scaffold",
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"import { FastMCP } from 'fastmcp';",
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"",
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f"const server = new FastMCP({{ name: '{server_name}' }});",
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"",
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*registrations,
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"",
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"server.run();",
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"",
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]
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)
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def write_outputs(server_name: str, language: str, output_dir: Path, tools: List[Dict[str, Any]]) -> GenerationSummary:
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output_dir.mkdir(parents=True, exist_ok=True)
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manifest_path = output_dir / "tool_manifest.json"
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manifest = {"server": server_name, "tools": tools}
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manifest_path.write_text(json.dumps(manifest, indent=2), encoding="utf-8")
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if language == "python":
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scaffold_path = output_dir / "server.py"
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scaffold_path.write_text(python_scaffold(server_name, tools), encoding="utf-8")
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else:
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scaffold_path = output_dir / "server.ts"
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scaffold_path.write_text(typescript_scaffold(server_name, tools), encoding="utf-8")
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return GenerationSummary(
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server_name=server_name,
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language=language,
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operations_total=len(tools),
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tools_generated=len(tools),
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output_dir=str(output_dir.resolve()),
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manifest_path=str(manifest_path.resolve()),
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scaffold_path=str(scaffold_path.resolve()),
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)
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def main() -> int:
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args = parse_args()
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raw = load_raw_input(args.input)
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spec = parse_openapi(raw)
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tools = extract_tools(spec)
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if not tools:
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raise CLIError("No operations discovered in OpenAPI paths.")
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summary = write_outputs(
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server_name=args.server_name,
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language=args.language,
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output_dir=Path(args.output_dir),
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tools=tools,
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)
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if args.format == "json":
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print(json.dumps(asdict(summary), indent=2))
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else:
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print("MCP scaffold generated")
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print(f"- server: {summary.server_name}")
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print(f"- language: {summary.language}")
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print(f"- tools: {summary.tools_generated}")
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print(f"- manifest: {summary.manifest_path}")
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print(f"- scaffold: {summary.scaffold_path}")
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return 0
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if __name__ == "__main__":
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try:
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raise SystemExit(main())
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except CLIError as exc:
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print(f"ERROR: {exc}", file=sys.stderr)
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raise SystemExit(2)
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