ExpressJS MCP

import type { RouteInfo } from "./index"; type OpenAPI = Record<string, unknown>; export class SchemaResolver { constructor( private options: { openapi?: Record<string, unknown>; schemaAnnotations?: Record<string, unknown>; } = {}, ) {} toolName(r: RouteInfo) { return `${r.method} ${r.path}`; } safeName(r: RouteInfo) { return this.toolName(r).replace(/\s+/g, "_"); } toTool(r: RouteInfo) { const key = this.toolName(r); const ann = this.options?.schemaAnnotations?.[key] ?? {}; const open = this.findOpenApiSchemas(r); return { name: this.safeName(r), title: key, description: ann.description ?? open.description ?? `Invoke ${r.method} ${r.path}`, inputSchema: ann.input ? this.zodToJsonSchema(ann.input) : (open.inputSchema ?? { type: "object", additionalProperties: true }), outputSchema: ann.output ? this.zodToJsonSchema(ann.output) : (open.outputSchema ?? { type: "object", additionalProperties: true }), examples: ann.examples ?? open.examples ?? [], route: { method: r.method, path: r.path }, }; } mergeEnrichment(_: RouteInfo, __: Partial<Record<string, unknown>>) { // No-op for now; reserved for future enrichers (e.g., manual docs). } private findOpenApiSchemas(r: RouteInfo) { const result: { inputSchema?: unknown; outputSchema?: unknown; description?: string; examples?: unknown[]; } = {}; const doc = this.options.openapi as Record<string, unknown>; if (!doc?.paths) return result; const pathItem = doc.paths[r.path]; if (!pathItem) return result; const op = pathItem[r.method.toLowerCase()]; if (!op) return result; result.description = op.summary || op.description; // requestBody const rb = op.requestBody?.content; if (rb) { const json = rb["application/json"]?.schema; if (json) result.inputSchema = json; } // responses: prefer 200/201 json const res = op.responses; const preferred = res?.["200"] ?? res?.["201"]; const content = preferred?.content; if (content) { const json = content["application/json"]?.schema; if (json) result.outputSchema = json; } // examples (best effort) const exIn = rb?.["application/json"]?.examples; const exOut = content?.["application/json"]?.examples; const toArr = (ex: unknown) => ex && typeof ex === "object" && ex !== null ? Object.values(ex) .map((e: unknown) => e && typeof e === "object" && "value" in e ? (e as { value: unknown }).value : null, ) .filter(Boolean) : []; result.examples = [...toArr(exIn), ...toArr(exOut)]; return result; } private zodToJsonSchema(z: unknown) { try { if (z && "parse" in z) { // eslint-disable-next-line @typescript-eslint/no-var-requires const { zodToJsonSchema } = require("zod-to-json-schema"); return zodToJsonSchema(z); } return z; } catch { return { type: "object" }; } } }