diff --git a/src/circuit/circuit/hop.js b/src/circuit/circuit/hop.js
index 59de474f..3c1730ce 100644
--- a/src/circuit/circuit/hop.js
+++ b/src/circuit/circuit/hop.js
@@ -18,15 +18,18 @@ const { stop } = require('./stop')
 const multicodec = require('./../multicodec')
 
 /**
+ * @typedef {import('../../types').CircuitRequest} Request
  * @typedef {import('libp2p-interfaces/src/connection').Connection} Connection
+ * @typedef {import('./stream-handler')<Request>} StreamHandlerT
+ * @typedef {import('../transport')} Transport
  */
 
 /**
  * @typedef {Object} HopRequest
  * @property {Connection} connection
- * @property {any} request
- * @property {any} streamHandler
- * @property {import('../transport')} circuit
+ * @property {Request} request
+ * @property {StreamHandlerT} streamHandler
+ * @property {Transport} circuit
  */
 
 /**
@@ -110,7 +113,7 @@ async function handleHop ({
  *
  * @param {object} options
  * @param {Connection} options.connection - Connection to the relay
- * @param {CircuitPB} options.request
+ * @param {Request} options.request
  * @returns {Promise<Connection>}
  */
 async function hop ({
@@ -168,8 +171,8 @@ async function canHop ({
  *
  * @param {Object} options
  * @param {Connection} options.connection
- * @param {StreamHandler} options.streamHandler
- * @param {import('../transport')} options.circuit
+ * @param {StreamHandlerT} options.streamHandler
+ * @param {Transport} options.circuit
  * @private
  */
 function handleCanHop ({
diff --git a/src/circuit/circuit/stop.js b/src/circuit/circuit/stop.js
index 827d68d3..2e41e48c 100644
--- a/src/circuit/circuit/stop.js
+++ b/src/circuit/circuit/stop.js
@@ -13,6 +13,8 @@ const { validateAddrs } = require('./utils')
 /**
  * @typedef {import('libp2p-interfaces/src/connection').Connection} Connection
  * @typedef {import('libp2p-interfaces/src/stream-muxer/types').MuxedStream} MuxedStream
+ * @typedef {import('../../types').CircuitRequest} Request
+ * @typedef {import('./stream-handler')<Request>} StreamHandlerT
  */
 
 /**
@@ -21,8 +23,8 @@ const { validateAddrs } = require('./utils')
  * @private
  * @param {Object} options
  * @param {Connection} options.connection
- * @param {CircuitPB} options.request - The CircuitRelay protobuf request (unencoded)
- * @param {StreamHandler} options.streamHandler
+ * @param {Request} options.request - The CircuitRelay protobuf request (unencoded)
+ * @param {StreamHandlerT} options.streamHandler
  * @returns {Promise<MuxedStream>|void} Resolves a duplex iterable
  */
 module.exports.handleStop = function handleStop ({
@@ -52,7 +54,7 @@ module.exports.handleStop = function handleStop ({
  * @private
  * @param {Object} options
  * @param {Connection} options.connection
- * @param {CircuitPB} options.request - The CircuitRelay protobuf request (unencoded)
+ * @param {Request} options.request - The CircuitRelay protobuf request (unencoded)
  * @returns {Promise<MuxedStream|void>} Resolves a duplex iterable
  */
 module.exports.stop = async function stop ({
diff --git a/src/circuit/circuit/stream-handler.js b/src/circuit/circuit/stream-handler.js
index d94576c5..5be2c6ed 100644
--- a/src/circuit/circuit/stream-handler.js
+++ b/src/circuit/circuit/stream-handler.js
@@ -9,13 +9,20 @@ const lp = require('it-length-prefixed')
 const handshake = require('it-handshake')
 const { CircuitRelay: CircuitPB } = require('../protocol')
 
+/**
+ * @typedef {import('libp2p-interfaces/src/stream-muxer/types').MuxedStream} MuxedStream
+ */
+
+/**
+ * @template T
+ */
 class StreamHandler {
   /**
    * Create a stream handler for connection
    *
    * @class
    * @param {object} options
-   * @param {import('libp2p-interfaces/src/stream-muxer/types').MuxedStream} options.stream - A duplex iterable
+   * @param {MuxedStream} options.stream - A duplex iterable
    * @param {number} [options.maxLength = 4096] - max bytes length of message
    */
   constructor ({ stream, maxLength = 4096 }) {
@@ -29,7 +36,7 @@ class StreamHandler {
    * Read and decode message
    *
    * @async
-   * @returns {Promise<CircuitPB>}
+   * @returns {Promise<T|undefined>}
    */
   async read () {
     const msg = await this.decoder.next()
diff --git a/src/circuit/transport.js b/src/circuit/transport.js
index 4eea0610..650bb97d 100644
--- a/src/circuit/transport.js
+++ b/src/circuit/transport.js
@@ -8,7 +8,6 @@ const log = Object.assign(debug('libp2p:circuit'), {
 const mafmt = require('mafmt')
 const multiaddr = require('multiaddr')
 const PeerId = require('peer-id')
-const withIs = require('class-is')
 const { CircuitRelay: CircuitPB } = require('./protocol')
 
 const toConnection = require('libp2p-utils/src/stream-to-ma-conn')
@@ -19,9 +18,12 @@ const { handleCanHop, handleHop, hop } = require('./circuit/hop')
 const { handleStop } = require('./circuit/stop')
 const StreamHandler = require('./circuit/stream-handler')
 
+const transportSymbol = Symbol.for('@libp2p/js-libp2p-circuit/circuit')
+
 /**
  * @typedef {import('multiaddr')} Multiaddr
  * @typedef {import('libp2p-interfaces/src/connection').Connection} Connection
+ * @typedef {import('libp2p-interfaces/src/stream-muxer/types').MuxedStream} MuxedStream
  */
 
 class Circuit {
@@ -45,6 +47,11 @@ class Circuit {
     this._registrar.handle(multicodec, this._onProtocol.bind(this))
   }
 
+  /**
+   * @param {Object} props
+   * @param {Connection} props.connection
+   * @param {MuxedStream} props.stream
+   */
   async _onProtocol ({ connection, stream }) {
     const streamHandler = new StreamHandler({ stream })
     const request = await streamHandler.read()
@@ -190,9 +197,20 @@ class Circuit {
       return mafmt.Circuit.matches(ma)
     })
   }
+
+  get [Symbol.toStringTag] () {
+    return 'Circuit'
+  }
+
+  /**
+   * Checks if the given value is a Transport instance.
+   *
+   * @param {any} other
+   * @returns {other is Transport}
+   */
+  static isTransport (other) {
+    return Boolean(other && other[transportSymbol])
+  }
 }
 
-/**
- * @type {Circuit}
- */
-module.exports = withIs(Circuit, { className: 'Circuit', symbolName: '@libp2p/js-libp2p-circuit/circuit' })
+module.exports = Circuit
diff --git a/src/connection-manager/visibility-change-emitter.js b/src/connection-manager/visibility-change-emitter.js
index b69ba78f..ebe5e7d0 100644
--- a/src/connection-manager/visibility-change-emitter.js
+++ b/src/connection-manager/visibility-change-emitter.js
@@ -13,8 +13,6 @@ const debug = require('debug')('latency-monitor:VisibilityChangeEmitter')
 /**
  * Listen to page visibility change events (i.e. when the page is focused / blurred) by an event emitter.
  *
- * @extends {EventEmitter}
- *
  * Warning: This does not work on all browsers, but should work on all modern browsers
  *
  * @example
diff --git a/src/dialer/index.js b/src/dialer/index.js
index c334d449..09ae2627 100644
--- a/src/dialer/index.js
+++ b/src/dialer/index.js
@@ -34,12 +34,14 @@ const {
  * @property {PeerStore} peerStore
  * @property {TransportManager} transportManager
  *
+ * @typedef {(addr:Multiaddr) => Promise<string[]>} Resolver
+ *
  * @typedef {Object} DialerOptions
- * @param {(addresses: Address[]) => Address[]} [options.addressSorter = publicAddressesFirst] - Sort the known addresses of a peer before trying to dial.
+ * @property {(addresses: Address[]) => Address[]} [options.addressSorter = publicAddressesFirst] - Sort the known addresses of a peer before trying to dial.
  * @property {number} [concurrency = MAX_PARALLEL_DIALS] - Number of max concurrent dials.
  * @property {number} [perPeerLimit = MAX_PER_PEER_DIALS] - Number of max concurrent dials per peer.
  * @property {number} [timeout = DIAL_TIMEOUT] - How long a dial attempt is allowed to take.
- * @property {Object} [resolvers = {}] - multiaddr resolvers to use when dialing
+ * @property {Record<string, Resolver>} [resolvers = {}] - multiaddr resolvers to use when dialing
  *
  * @typedef DialTarget
  * @property {string} id
@@ -240,13 +242,13 @@ class Dialer {
       return this._resolve(nm)
     }))
 
-    return recursiveMultiaddrs.flat()
-      .reduce((/** @type {Multiaddr[]} */ array, /** @type {Multiaddr} */ newM) => {
-        if (!array.find(m => m.equals(newM))) {
-          array.push(newM)
-        }
-        return array
-      }, []) // Unique addresses
+    const addrs = recursiveMultiaddrs.flat()
+    return addrs.reduce((array, newM) => {
+      if (!array.find(m => m.equals(newM))) {
+        array.push(newM)
+      }
+      return array
+    }, /** @type  {Multiaddr[]} */([]))
   }
 
   /**
diff --git a/src/index.js b/src/index.js
index 8c04e4d8..7e620403 100644
--- a/src/index.js
+++ b/src/index.js
@@ -57,11 +57,11 @@ const IDENTIFY_PROTOCOLS = IdentifyService.multicodecs
  * @property {import('./circuit').AutoRelayOptions} autoRelay
  *
  * @typedef {Object} Libp2pConfig
- * @property {any} [dht] dht module options
+ * @property {Object} [dht] dht module options
  * @property {PeerDiscoveryOptions} [peerDiscovery]
  * @property {Pubsub} [pubsub] pubsub module options
  * @property {RelayOptions} [relay]
- * @property {Object} [transport] transport options indexed by transport key
+ * @property {Record<string, Object>} [transport] transport options indexed by transport key
  *
  * @typedef {Object} Libp2pModules
  * @property {TransportFactory[]} transport
@@ -141,7 +141,6 @@ class Libp2p extends EventEmitter {
 
       const keychainOpts = Keychain.generateOptions()
 
-      /** @type {Keychain} */
       this.keychain = new Keychain(this._options.keychain.datastore, {
         passPhrase: this._options.keychain.pass,
         ...keychainOpts,
@@ -350,6 +349,10 @@ class Libp2p extends EventEmitter {
    * @returns {Promise<void>}
    */
   async loadKeychain () {
+    if (!this.keychain) {
+      return
+    }
+
     try {
       await this.keychain.findKeyByName('self')
     } catch (err) {
@@ -381,7 +384,7 @@ class Libp2p extends EventEmitter {
    * @returns {Promise<Connection>}
    */
   dial (peer, options) {
-    return this.dialProtocol(peer, undefined, options)
+    return this.dialProtocol(peer, [], options)
   }
 
   /**
@@ -391,7 +394,7 @@ class Libp2p extends EventEmitter {
    *
    * @async
    * @param {PeerId|Multiaddr|string} peer - The peer to dial
-   * @param {undefined|string[]|string} protocols
+   * @param {null|string[]|string} protocols
    * @param {object} [options]
    * @param {AbortSignal} [options.signal]
    * @returns {Promise<Connection|*>}
@@ -407,7 +410,7 @@ class Libp2p extends EventEmitter {
     }
 
     // If a protocol was provided, create a new stream
-    if (protocols) {
+    if (protocols && protocols.length) {
       return connection.newStream(protocols)
     }
 
diff --git a/src/keychain/cms.js b/src/keychain/cms.js
index c808ed69..3ba99cfb 100644
--- a/src/keychain/cms.js
+++ b/src/keychain/cms.js
@@ -22,7 +22,7 @@ class CMS {
   /**
    * Creates a new instance with a keychain
    *
-   * @param {Keychain} keychain - the available keys
+   * @param {import('./index')} keychain - the available keys
    */
   constructor (keychain) {
     if (!keychain) {
@@ -39,7 +39,7 @@ class CMS {
    *
    * @param {string} name - The local key name.
    * @param {Uint8Array} plain - The data to encrypt.
-   * @returns {undefined}
+   * @returns {Promise<Uint8Array>}
    */
   async encrypt (name, plain) {
     if (!(plain instanceof Uint8Array)) {
@@ -69,7 +69,7 @@ class CMS {
    * exists, an Error is returned with the property 'missingKeys'.  It is array of key ids.
    *
    * @param {Uint8Array} cmsData - The CMS encrypted data to decrypt.
-   * @returns {undefined}
+   * @returns {Promise<Uint8Array>}
    */
   async decrypt (cmsData) {
     if (!(cmsData instanceof Uint8Array)) {
diff --git a/src/peer-store/address-book.js b/src/peer-store/address-book.js
index 516d908f..74b6049a 100644
--- a/src/peer-store/address-book.js
+++ b/src/peer-store/address-book.js
@@ -206,7 +206,7 @@ class AddressBook extends Book {
     log(`stored provided multiaddrs for ${id}`)
 
     // Notify the existance of a new peer
-    if (!(entry && entry.addresses)) {
+    if (!entry) {
       this._ps.emit('peer', peerId)
     }
 
diff --git a/src/types.ts b/src/types.ts
index fe58c0e5..3e87d7c8 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -43,6 +43,17 @@ export type CAN_HOP = 4;
 
 export type CircuitType = HOP | STOP | STATUS | CAN_HOP
 
+export type CircuitPeer = {
+  id: Uint8Array
+  addrs: Uint8Array[]
+}
+
+export type CircuitRequest = {
+  type: CircuitType
+  dstPeer: CircuitPeer
+  srcPeer: CircuitPeer
+}
+
 export type CircuitMessageProto = {
   encode(value: any): Uint8Array
   decode(bytes: Uint8Array): any