// MCP from OpenAPI - Tool Generator and Request Builder
// Uses mcp-from-openapi package
import { OpenAPIToolGenerator, McpOpenAPITool } from 'mcp-from-openapi';
export interface MCPToolOutput {
content: Array<{ type: string; text: string }>;
isError: boolean;
}
/**
* Execute a tool by name
* 1. Find tool and build HTTP request using mapper
* 2. Execute fetch
* 3. Convert response to MCP output
*/
export async function executeTool(
tools: McpOpenAPITool[],
toolName: string,
input: Record<string, unknown>,
baseUrl: string,
authToken?: string
): Promise<MCPToolOutput> {
// Find tool
const tool = tools.find((t) => t.name === toolName);
if (!tool) {
return {
content: [{ type: 'text', text: `Tool "${toolName}" not found` }],
isError: true,
};
}
// 1. Build HTTP Request from tool mapper
let url = baseUrl + tool.metadata.path;
const headers: Record<string, string> = { 'Content-Type': 'application/json' };
// Add auth token if provided
if (authToken) {
headers['Authorization'] = authToken.startsWith('Bearer ') ? authToken : `Bearer ${authToken}`;
}
const queryParams: Record<string, string> = {};
let body: unknown = null;
for (const mapping of tool.mapper) {
const value = input[mapping.inputKey];
if (value === undefined) continue;
switch (mapping.type) {
case 'path':
url = url.replace(`{${mapping.key}}`, encodeURIComponent(String(value)));
break;
case 'query':
queryParams[mapping.key] = String(value);
break;
case 'header':
headers[mapping.key] = String(value);
break;
case 'body':
body = value;
break;
}
}
const queryString = new URLSearchParams(queryParams).toString();
if (queryString) url += `?${queryString}`;
// 2. Execute fetch
const response = await fetch(url, {
method: tool.metadata.method.toUpperCase(),
headers,
body: body ? JSON.stringify(body) : undefined,
});
// 3. Convert response to MCP output
const contentType = response.headers.get('content-type');
let resultText: string;
if (contentType?.includes('application/json')) {
const data = await response.json();
resultText = JSON.stringify(data, null, 2);
} else {
resultText = await response.text();
}
return {
content: [{ type: 'text', text: resultText }],
isError: !response.ok,
};
}
/**
* Create generator from spec URL or JSON object
*/
export async function createGenerator(
specOrUrl: string | object,
baseUrl?: string
): Promise<OpenAPIToolGenerator> {
if (typeof specOrUrl === 'string') {
return OpenAPIToolGenerator.fromURL(specOrUrl, { baseUrl, validate: true });
}
return OpenAPIToolGenerator.fromJSON(specOrUrl, { baseUrl, validate: true });
}
