diff --git a/scripts/hooks/mcp-health-check.js b/scripts/hooks/mcp-health-check.js
index 475e4aa73..b78b5ac57 100644
--- a/scripts/hooks/mcp-health-check.js
+++ b/scripts/hooks/mcp-health-check.js
@@ -28,8 +28,11 @@ const MAX_BACKOFF_MS = 10 * 60 * 1000;
 // Claude Code's stored OAuth bearer token. Treat auth-gated responses as
 // reachable so the real MCP client can attempt the authenticated call. A
 // Streamable HTTP MCP server can also return 406 to a bare GET that omits
-// Accept: text/event-stream; that still proves the endpoint is alive.
-const HEALTHY_HTTP_CODES = new Set([200, 201, 202, 204, 301, 302, 303, 304, 307, 308, 400, 401, 403, 405, 406]);
+// Accept: text/event-stream; that still proves the endpoint is alive. Some
+// POST-only Streamable HTTP servers (e.g. Paper Desktop) answer a bare GET
+// with 404 instead; a routed HTTP response of any kind proves reachability,
+// so treat 404 as alive and let the real MCP client validate the endpoint.
+const HEALTHY_HTTP_CODES = new Set([200, 201, 202, 204, 301, 302, 303, 304, 307, 308, 400, 401, 403, 404, 405, 406]);
 const RECONNECT_STATUS_CODES = new Set([401, 403, 429, 503]);
 const FAILURE_PATTERNS = [
   { code: 401, pattern: /\b401\b|unauthori[sz]ed|auth(?:entication)?\s+(?:failed|expired|invalid)/i },
diff --git a/scripts/memory-mcp.mjs b/scripts/memory-mcp.mjs
index 5cde5e80e..7821efbfc 100755
--- a/scripts/memory-mcp.mjs
+++ b/scripts/memory-mcp.mjs
@@ -423,8 +423,16 @@ function createMemoryMcpService(options = {}) {
         return jsonRpcResult(message.id, {});
       }
       if (message.method === 'tools/list') {
-        if (message.params && Object.keys(message.params).length > 0) {
-          return jsonRpcError(message.id, -32602, 'tools/list does not accept parameters.');
+        const params = message.params || {};
+        if (
+          (Object.prototype.hasOwnProperty.call(params, '_meta') && !isRecord(params._meta))
+          || (
+            Object.prototype.hasOwnProperty.call(params, 'cursor')
+            && typeof params.cursor !== 'string'
+          )
+          || Object.keys(params).some(key => !['cursor', '_meta'].includes(key))
+        ) {
+          return jsonRpcError(message.id, -32602, 'Invalid tools/list parameters.');
         }
         return jsonRpcResult(message.id, {
           tools: TOOL_DEFINITIONS.map(tool => ({ ...tool })),
diff --git a/tests/hooks/mcp-health-check.test.js b/tests/hooks/mcp-health-check.test.js
index fa05fa670..fe86290e4 100644
--- a/tests/hooks/mcp-health-check.test.js
+++ b/tests/hooks/mcp-health-check.test.js
@@ -888,6 +888,77 @@ async function runTests() {
     }
   })) passed++; else failed++;
 
+  if (await asyncTest('treats HTTP 404 probe responses as healthy POST-only Streamable HTTP servers', async () => {
+    const tempDir = createTempDir();
+    const configPath = path.join(tempDir, 'claude.json');
+    const statePath = path.join(tempDir, 'mcp-health.json');
+    const serverScript = path.join(tempDir, 'http-404-server.js');
+    const portFile = path.join(tempDir, 'server-port.txt');
+
+    // Mirrors Paper Desktop: the Streamable HTTP endpoint only routes POST and
+    // answers a bare GET probe with 404, which still proves reachability.
+    fs.writeFileSync(
+      serverScript,
+      [
+        "const fs = require('fs');",
+        "const http = require('http');",
+        "const portFile = process.argv[2];",
+        "const server = http.createServer((req, res) => {",
+        "  if (req.method === 'POST' && req.url === '/mcp') {",
+        "    res.writeHead(200, { 'Content-Type': 'text/event-stream' });",
+        "    res.end('event: message\\ndata: {}\\n\\n');",
+        "    return;",
+        "  }",
+        "  res.writeHead(404, { 'Content-Type': 'text/plain' });",
+        "  res.end('not found');",
+        "});",
+        "server.listen(0, '127.0.0.1', () => {",
+        "  fs.writeFileSync(portFile, String(server.address().port));",
+        "});",
+        "setInterval(() => {}, 1000);"
+      ].join('\n')
+    );
+
+    const serverProcess = spawn(process.execPath, [serverScript, portFile], {
+      stdio: 'ignore'
+    });
+
+    try {
+      const port = waitForFile(portFile).trim();
+      await waitForHttpReady(`http://127.0.0.1:${port}/mcp`);
+
+      writeConfig(configPath, {
+        mcpServers: {
+          http404: {
+            type: 'http',
+            url: `http://127.0.0.1:${port}/mcp`
+          }
+        }
+      });
+
+      const input = { tool_name: 'mcp__http404__get_guide', tool_input: {} };
+      const result = runHook(input, {
+        CLAUDE_HOOK_EVENT_NAME: 'PreToolUse',
+        ECC_MCP_CONFIG_PATH: configPath,
+        ECC_MCP_HEALTH_STATE_PATH: statePath,
+        ECC_MCP_HEALTH_TIMEOUT_MS: '2000'
+      });
+
+      assert.strictEqual(
+        result.code,
+        0,
+        `Expected HTTP 404 probe to be treated as healthy: ${hookFailureDetails(result, statePath)}`
+      );
+      assert.strictEqual(result.stdout.trim(), JSON.stringify(input), 'Expected original JSON on stdout');
+
+      const state = readState(statePath);
+      assert.strictEqual(state.servers.http404.status, 'healthy', 'Expected POST-only HTTP MCP server to be marked healthy');
+    } finally {
+      serverProcess.kill('SIGTERM');
+      cleanupTempDir(tempDir);
+    }
+  })) passed++; else failed++;
+
   if (await asyncTest('treats HTTP 401 probe responses as healthy reachable OAuth-protected servers', async () => {
     const tempDir = createTempDir();
     const configPath = path.join(tempDir, 'claude.json');
diff --git a/tests/scripts/memory-mcp.test.js b/tests/scripts/memory-mcp.test.js
index 0a3a7a7a0..a234d28a6 100644
--- a/tests/scripts/memory-mcp.test.js
+++ b/tests/scripts/memory-mcp.test.js
@@ -132,6 +132,7 @@ async function withClient(fn, options = {}) {
 
   const client = {
     listTools: () => request('tools/list'),
+    listToolsRaw: params => request('tools/list', params),
     callTool: ({ name, arguments: toolArguments }) => request(
       'tools/call',
       { name, arguments: toolArguments }
@@ -181,6 +182,51 @@ async function main() {
     });
   });
 
+  await test('accepts reserved tools/list params and rejects malformed values', async () => {
+    await withClient(async client => {
+      const withMeta = await client.listToolsRaw({
+        _meta: { progressToken: 'progress-123' },
+      });
+      assert.strictEqual(withMeta.tools.length, 4);
+
+      const withCursor = await client.listToolsRaw({ cursor: 'next-page' });
+      assert.strictEqual(withCursor.tools.length, 4);
+
+      const withCursorAndMeta = await client.listToolsRaw({
+        cursor: 'next-page',
+        _meta: { progressToken: 'progress-456' },
+      });
+      assert.strictEqual(withCursorAndMeta.tools.length, 4);
+
+      const withoutMeta = await client.listTools();
+      assert.deepStrictEqual(
+        withoutMeta.tools.map(tool => tool.name).sort(),
+        ['memory_doctor', 'memory_read', 'memory_save', 'memory_search']
+      );
+
+      for (const badMeta of [null, ['not', 'an', 'object'], 'string', 42, true]) {
+        await assert.rejects(
+          client.listToolsRaw({ _meta: badMeta }),
+          /-32602/,
+          `expected _meta=${JSON.stringify(badMeta)} to be rejected`
+        );
+      }
+
+      for (const badCursor of [null, {}, [], 42, true]) {
+        await assert.rejects(
+          client.listToolsRaw({ cursor: badCursor }),
+          /-32602/,
+          `expected cursor=${JSON.stringify(badCursor)} to be rejected`
+        );
+      }
+
+      await assert.rejects(
+        client.listToolsRaw({ unexpected: true }),
+        /-32602/
+      );
+    });
+  });
+
   await test('accepts the reserved _meta param on tools/call and rejects malformed values', async () => {
     await withClient(async client => {
       // A valid `_meta` object (e.g. progressToken) must not block the tool call.