feat: add logs tool (#114)

Author: nirinchev

src/tools/mongodb/metadata/logs.ts

@@ -0,0 +1,55 @@
+import { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
+import { MongoDBToolBase } from "../mongodbTool.js";
+import { ToolArgs, OperationType } from "../../tool.js";
+import { z } from "zod";
+
+export class LogsTool extends MongoDBToolBase {
+    protected name = "mongodb-logs";
+    protected description = "Returns the most recent logged mongod events";
+    protected argsShape = {
+        type: z
+            .enum(["global", "startupWarnings"])
+            .optional()
+            .default("global")
+            .describe(
+                "The type of logs to return. Global returns all recent log entries, while startupWarnings returns only warnings and errors from when the process started."
+            ),
+        limit: z
+            .number()
+            .int()
+            .max(1024)
+            .min(1)
+            .optional()
+            .default(50)
+            .describe("The maximum number of log entries to return."),
+    };
+
+    protected operationType: OperationType = "metadata";
+
+    protected async execute({ type, limit }: ToolArgs<typeof this.argsShape>): Promise<CallToolResult> {
+        const provider = await this.ensureConnected();
+
+        const result = await provider.runCommandWithCheck("admin", {
+            getLog: type,
+        });
+
+        const logs = (result.log as string[]).slice(0, limit);
+
+        return {
+            content: [
+                {
+                    text: `Found: ${result.totalLinesWritten} messages`,
+                    type: "text",
+                },
+
+                ...logs.map(
+                    (log) =>
+                        ({
+                            text: log,
+                            type: "text",
+                        }) as const
+                ),
+            ],
+        };
+    }
+}

src/tools/mongodb/tools.ts

@@ -17,6 +17,7 @@ import { DropDatabaseTool } from "./delete/dropDatabase.js";
 import { DropCollectionTool } from "./delete/dropCollection.js";
 import { ExplainTool } from "./metadata/explain.js";
 import { CreateCollectionTool } from "./create/createCollection.js";
+import { LogsTool } from "./metadata/logs.js";
 
 export const MongoDbTools = [
     ConnectTool,
@@ -38,4 +39,5 @@ export const MongoDbTools = [
     DropCollectionTool,
     ExplainTool,
     CreateCollectionTool,
+    LogsTool,
 ];

tests/integration/helpers.ts

@@ -101,13 +101,17 @@ export function setupIntegrationTest(userConfig: UserConfig = config): Integrati
     };
 }
 
-export function getResponseContent(content: unknown): string {
+export function getResponseContent(content: unknown | { content: unknown }): string {
     return getResponseElements(content)
         .map((item) => item.text)
         .join("\n");
 }
 
-export function getResponseElements(content: unknown): { type: string; text: string }[] {
+export function getResponseElements(content: unknown | { content: unknown }): { type: string; text: string }[] {
+    if (typeof content === "object" && content !== null && "content" in content) {
+        content = (content as { content: unknown }).content;
+    }
+
     expect(Array.isArray(content)).toBe(true);
 
     const response = content as { type: string; text: string }[];

tests/integration/tools/mongodb/delete/dropDatabase.test.ts

@@ -21,7 +21,7 @@ describeWithMongoDB("dropDatabase tool", (integration) => {
     it("can drop non-existing database", async () => {
         let { databases } = await integration.mongoClient().db("").admin().listDatabases();
 
-        const preDropLength = databases.length;
+        expect(databases.find((db) => db.name === integration.randomDbName())).toBeUndefined();
 
         await integration.connectMcpClient();
         const response = await integration.mcpClient().callTool({
@@ -36,7 +36,6 @@ describeWithMongoDB("dropDatabase tool", (integration) => {
 
         ({ databases } = await integration.mongoClient().db("").admin().listDatabases());
 
-        expect(databases).toHaveLength(preDropLength);
         expect(databases.find((db) => db.name === integration.randomDbName())).toBeUndefined();
     });
 

tests/integration/tools/mongodb/metadata/dbStats.test.ts

@@ -82,15 +82,13 @@ describeWithMongoDB("dbStats tool", (integration) => {
         }
     });
 
-    describe("when not connected", () => {
-        validateAutoConnectBehavior(integration, "db-stats", () => {
-            return {
-                args: {
-                    database: integration.randomDbName(),
-                    collection: "foo",
-                },
-                expectedResponse: `Statistics for database ${integration.randomDbName()}`,
-            };
-        });
+    validateAutoConnectBehavior(integration, "db-stats", () => {
+        return {
+            args: {
+                database: integration.randomDbName(),
+                collection: "foo",
+            },
+            expectedResponse: `Statistics for database ${integration.randomDbName()}`,
+        };
     });
 });

tests/integration/tools/mongodb/metadata/logs.test.ts

@@ -0,0 +1,83 @@
+import { validateToolMetadata, validateThrowsForInvalidArguments, getResponseElements } from "../../../helpers.js";
+import { describeWithMongoDB, validateAutoConnectBehavior } from "../mongodbHelpers.js";
+
+describeWithMongoDB("logs tool", (integration) => {
+    validateToolMetadata(integration, "mongodb-logs", "Returns the most recent logged mongod events", [
+        {
+            type: "string",
+            name: "type",
+            description:
+                "The type of logs to return. Global returns all recent log entries, while startupWarnings returns only warnings and errors from when the process started.",
+            required: false,
+        },
+        {
+            type: "integer",
+            name: "limit",
+            description: "The maximum number of log entries to return.",
+            required: false,
+        },
+    ]);
+
+    validateThrowsForInvalidArguments(integration, "mongodb-logs", [
+        { extra: true },
+        { type: 123 },
+        { type: "something" },
+        { limit: 0 },
+        { limit: true },
+        { limit: 1025 },
+    ]);
+
+    it("should return global logs", async () => {
+        await integration.connectMcpClient();
+        const response = await integration.mcpClient().callTool({
+            name: "mongodb-logs",
+            arguments: {},
+        });
+
+        const elements = getResponseElements(response);
+
+        // Default limit is 50
+        expect(elements.length).toBeLessThanOrEqual(51);
+        expect(elements[0].text).toMatch(/Found: \d+ messages/);
+
+        for (let i = 1; i < elements.length; i++) {
+            const log = JSON.parse(elements[i].text);
+            expect(log).toHaveProperty("t");
+            expect(log).toHaveProperty("msg");
+        }
+    });
+
+    it("should return startupWarnings logs", async () => {
+        await integration.connectMcpClient();
+        const response = await integration.mcpClient().callTool({
+            name: "mongodb-logs",
+            arguments: {
+                type: "startupWarnings",
+            },
+        });
+
+        const elements = getResponseElements(response);
+        expect(elements.length).toBeLessThanOrEqual(51);
+        for (let i = 1; i < elements.length; i++) {
+            const log = JSON.parse(elements[i].text);
+            expect(log).toHaveProperty("t");
+            expect(log).toHaveProperty("msg");
+            expect(log).toHaveProperty("tags");
+            expect(log.tags).toContain("startupWarnings");
+        }
+    });
+
+    validateAutoConnectBehavior(integration, "mongodb-logs", () => {
+        return {
+            args: {
+                database: integration.randomDbName(),
+                collection: "foo",
+            },
+            validate: (content) => {
+                const elements = getResponseElements(content);
+                expect(elements.length).toBeLessThanOrEqual(51);
+                expect(elements[0].text).toMatch(/Found: \d+ messages/);
+            },
+        };
+    });
+});