feat(tests): add unit tests for MCP tool registration and validation

- Introduced a new test file `server.test.ts` to validate MCP tool registration.
- Added tests to ensure at least one tool is registered, uniqueness of tool names, and compliance with naming and description constraints.
- Updated the description of the `currents-list-affected-tests` tool for clarity.

Author: agoldis

mcp-server/src/server.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, it, vi } from "vitest";
+
+const { registeredTools } = vi.hoisted(() => {
+  const registeredTools: Array<{ name: string; description: string }> = [];
+  return { registeredTools };
+});
+
+vi.mock("@modelcontextprotocol/sdk/server/mcp.js", () => ({
+  McpServer: class {
+    registerTool(
+      name: string,
+      opts: { description: string; inputSchema: unknown },
+      _handler: unknown
+    ) {
+      registeredTools.push({ name, description: opts.description });
+    }
+  },
+}));
+
+vi.mock("@modelcontextprotocol/sdk/server/stdio.js", () => ({
+  StdioServerTransport: class {},
+}));
+
+// Triggers all registerTool calls at module scope
+import "./server.js";
+
+// SEP-986 (Final): tool names SHOULD be 1–64 characters
+const TOOL_NAME_MAX_LENGTH = 64;
+// Allowed: a-zA-Z0-9 _ - . /
+const TOOL_NAME_PATTERN = /^[a-zA-Z0-9_\-./]+$/;
+// No hard spec limit; 1024 is the practical ceiling across major LLM providers
+const TOOL_DESCRIPTION_MAX_LENGTH = 1024;
+
+describe("MCP tool best practices", () => {
+  it("has at least one registered tool", () => {
+    expect(registeredTools.length).toBeGreaterThan(0);
+  });
+
+  it("tool names are unique", () => {
+    const names = registeredTools.map((t) => t.name);
+    const dupes = names.filter((n, i) => names.indexOf(n) !== i);
+    expect(dupes, `duplicate tool names: ${dupes.join(", ")}`).toHaveLength(0);
+  });
+
+  describe.each(registeredTools)("$name", ({ name, description }) => {
+    // ── name constraints (SEP-986) ──────────────────────────────
+    it(`name length ≤ ${TOOL_NAME_MAX_LENGTH}`, () => {
+      expect(
+        name.length,
+        `"${name}" is ${name.length} chars`
+      ).toBeLessThanOrEqual(TOOL_NAME_MAX_LENGTH);
+    });
+
+    it("name contains only allowed characters", () => {
+      expect(name).toMatch(TOOL_NAME_PATTERN);
+    });
+
+    it("name is not empty", () => {
+      expect(name.length).toBeGreaterThan(0);
+    });
+
+    // ── description constraints ─────────────────────────────────
+    it("description is not empty", () => {
+      expect(description.length).toBeGreaterThan(0);
+    });
+
+    it(`description length ≤ ${TOOL_DESCRIPTION_MAX_LENGTH}`, () => {
+      expect(
+        description.length,
+        `description is ${description.length} chars`
+      ).toBeLessThanOrEqual(TOOL_DESCRIPTION_MAX_LENGTH);
+    });
+
+    it("description has no leading/trailing whitespace", () => {
+      expect(description).toBe(description.trim());
+    });
+
+    it("description starts with a capital letter", () => {
+      expect(description).toMatch(/^[A-Z]/);
+    });
+
+    it("description ends with a period", () => {
+      expect(description.at(-1)).toBe(".");
+    });
+  });
+});

mcp-server/src/server.ts

@@ -124,7 +124,7 @@ server.registerTool(
   "currents-list-affected-tests",
   {
     description:
-      "List tests affected by actions (quarantine, skip, tag) for a project within a date range. Returns aggregated data grouped by test signature. Supports filtering by action types, action ID, status, and search. Requires projectId, date_start, and date_end. (Preview endpoint: fields and path may change.)",
+      "List tests affected by actions (quarantine, skip, tag) for a project within a date range. Returns aggregated data grouped by test signature. Supports filtering by action types, action ID, status, and search. Requires projectId, date_start, and date_end. Preview endpoint: fields and path may change.",
     inputSchema: listAffectedTestsTool.schema,
   },
   listAffectedTestsTool.handler