diff --git a/internal/lsp/cache/check.go b/internal/lsp/cache/check.go
index 3bc6f05ad2..16a05934eb 100644
--- a/internal/lsp/cache/check.go
+++ b/internal/lsp/cache/check.go
@@ -102,6 +102,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 		return nil, errors.Errorf("no metadata for %v", id)
 	}
 	pkg := &pkg{
+		view:       imp.view,
 		id:         meta.id,
 		pkgPath:    meta.pkgPath,
 		imports:    make(map[packagePath]*pkg),
diff --git a/internal/lsp/cache/gofile.go b/internal/lsp/cache/gofile.go
index 0aae9c9ef7..f8948c16b1 100644
--- a/internal/lsp/cache/gofile.go
+++ b/internal/lsp/cache/gofile.go
@@ -63,6 +63,7 @@ func (f *goFile) GetToken(ctx context.Context) (*token.File, error) {
 func (f *goFile) GetAST(ctx context.Context, mode source.ParseMode) (*ast.File, error) {
 	f.view.mu.Lock()
 	defer f.view.mu.Unlock()
+
 	ctx = telemetry.File.With(ctx, f.URI())
 
 	if f.isDirty(ctx) || f.wrongParseMode(ctx, mode) {
@@ -70,8 +71,17 @@ func (f *goFile) GetAST(ctx context.Context, mode source.ParseMode) (*ast.File,
 			return nil, errors.Errorf("GetAST: unable to check package for %s: %v", f.URI(), err)
 		}
 	}
-	fh := f.Handle(ctx)
 	// Check for a cached AST first, in case getting a trimmed version would actually cause a re-parse.
+	fh := f.Handle(ctx)
+	cached, err := f.view.session.cache.cachedAST(fh, mode)
+	if cached != nil || err != nil {
+		return cached, err
+	}
+	ph := f.view.session.cache.ParseGoHandle(fh, mode)
+	return ph.Parse(ctx)
+}
+
+func (cache *cache) cachedAST(fh source.FileHandle, mode source.ParseMode) (*ast.File, error) {
 	for _, m := range []source.ParseMode{
 		source.ParseHeader,
 		source.ParseExported,
@@ -80,15 +90,14 @@ func (f *goFile) GetAST(ctx context.Context, mode source.ParseMode) (*ast.File,
 		if m < mode {
 			continue
 		}
-		if v, ok := f.view.session.cache.store.Cached(parseKey{
+		if v, ok := cache.store.Cached(parseKey{
 			file: fh.Identity(),
 			mode: m,
 		}).(*parseGoData); ok {
 			return v.ast, v.err
 		}
 	}
-	ph := f.view.session.cache.ParseGoHandle(fh, mode)
-	return ph.Parse(ctx)
+	return nil, nil
 }
 
 func (f *goFile) GetPackages(ctx context.Context) []source.Package {
@@ -126,13 +135,35 @@ func (f *goFile) GetPackage(ctx context.Context) source.Package {
 	// This solves the problem of test variants,
 	// as the test will have more files than the non-test package.
 	for _, pkg := range pkgs {
-		if result == nil || len(pkg.GetFilenames()) < len(result.GetFilenames()) {
+		if result == nil || len(pkg.GetHandles()) < len(result.GetHandles()) {
 			result = pkg
 		}
 	}
 	return result
 }
 
+func (f *goFile) GetCachedPackage(ctx context.Context) (source.Package, error) {
+	f.view.mu.Lock()
+	defer f.view.mu.Unlock()
+
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	var result source.Package
+	// Pick the "narrowest" package, i.e. the package with the fewest number of files.
+	// This solves the problem of test variants,
+	// as the test will have more files than the non-test package.
+	for _, pkg := range f.pkgs {
+		if result == nil || len(pkg.GetHandles()) < len(result.GetHandles()) {
+			result = pkg
+		}
+	}
+	if result == nil {
+		return nil, errors.Errorf("no cached package for %s", f.URI())
+	}
+	return result, nil
+}
+
 func (f *goFile) wrongParseMode(ctx context.Context, mode source.ParseMode) bool {
 	f.mu.Lock()
 	defer f.mu.Unlock()
diff --git a/internal/lsp/cache/parse.go b/internal/lsp/cache/parse.go
index b842f8452c..6f0f3edfd8 100644
--- a/internal/lsp/cache/parse.go
+++ b/internal/lsp/cache/parse.go
@@ -74,6 +74,15 @@ func (h *parseGoHandle) Parse(ctx context.Context) (*ast.File, error) {
 	return data.ast, data.err
 }
 
+func (h *parseGoHandle) Cached(ctx context.Context) (*ast.File, error) {
+	v := h.handle.Cached()
+	if v == nil {
+		return nil, errors.Errorf("no cached value for %s", h.file.Identity().URI)
+	}
+	data := v.(*parseGoData)
+	return data.ast, data.err
+}
+
 func parseGo(ctx context.Context, c *cache, fh source.FileHandle, mode source.ParseMode) (*ast.File, error) {
 	ctx, done := trace.StartSpan(ctx, "cache.parseGo", telemetry.File.Of(fh.Identity().URI.Filename()))
 	defer done()
diff --git a/internal/lsp/cache/pkg.go b/internal/lsp/cache/pkg.go
index c261079d40..6d357c6221 100644
--- a/internal/lsp/cache/pkg.go
+++ b/internal/lsp/cache/pkg.go
@@ -18,6 +18,8 @@ import (
 
 // pkg contains the type information needed by the source package.
 type pkg struct {
+	view *view
+
 	// ID and package path have their own types to avoid being used interchangeably.
 	id      packageID
 	pkgPath packagePath
@@ -147,18 +149,14 @@ func (pkg *pkg) PkgPath() string {
 	return string(pkg.pkgPath)
 }
 
-func (pkg *pkg) GetFilenames() []string {
-	filenames := make([]string, 0, len(pkg.files))
-	for _, ph := range pkg.files {
-		filenames = append(filenames, ph.File().Identity().URI.Filename())
-	}
-	return filenames
+func (pkg *pkg) GetHandles() []source.ParseGoHandle {
+	return pkg.files
 }
 
 func (pkg *pkg) GetSyntax(ctx context.Context) []*ast.File {
 	var syntax []*ast.File
 	for _, ph := range pkg.files {
-		file, _ := ph.Parse(ctx)
+		file, _ := ph.Cached(ctx)
 		if file != nil {
 			syntax = append(syntax, file)
 		}
diff --git a/internal/lsp/lsp_test.go b/internal/lsp/lsp_test.go
index a1588d46fb..df629f6ace 100644
--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@@ -162,7 +162,12 @@ func summarizeDiagnostics(i int, want []source.Diagnostic, got []source.Diagnost
 }
 
 func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests.CompletionSnippets, items tests.CompletionItems) {
-	defer func() { r.server.useDeepCompletions = false }()
+	defer func() {
+		r.server.useDeepCompletions = false
+		r.server.wantCompletionDocumentation = false
+	}()
+
+	r.server.wantCompletionDocumentation = true
 
 	for src, itemList := range data {
 		var want []source.CompletionItem
@@ -279,6 +284,11 @@ func diffCompletionItems(t *testing.T, spn span.Span, want []source.CompletionIt
 		if w.Detail != g.Detail {
 			return summarizeCompletionItems(i, want, got, "incorrect Detail got %v want %v", g.Detail, w.Detail)
 		}
+		if w.Documentation != "" && !strings.HasPrefix(w.Documentation, "@") {
+			if w.Documentation != g.Documentation {
+				return summarizeCompletionItems(i, want, got, "incorrect Documentation got %v want %v", g.Documentation, w.Documentation)
+			}
+		}
 		if wkind := toProtocolCompletionItemKind(w.Kind); wkind != g.Kind {
 			return summarizeCompletionItems(i, want, got, "incorrect Kind got %v want %v", g.Kind, wkind)
 		}
diff --git a/internal/lsp/source/completion_format.go b/internal/lsp/source/completion_format.go
index a07d8091cb..b724c77585 100644
--- a/internal/lsp/source/completion_format.go
+++ b/internal/lsp/source/completion_format.go
@@ -96,36 +96,44 @@ func (c *completer) item(cand candidate) (CompletionItem, error) {
 		plainSnippet:       plainSnippet,
 		placeholderSnippet: placeholderSnippet,
 	}
+	// TODO(rstambler): Log errors when this feature is enabled.
 	if c.opts.WantDocumentaton {
 		declRange, err := objToRange(c.ctx, c.view.Session().Cache().FileSet(), obj)
 		if err != nil {
-			log.Error(c.ctx, "failed to get declaration range for object", err, tag.Of("Name", obj.Name()))
 			goto Return
 		}
 		pos := declRange.FileSet.Position(declRange.Start)
 		if !pos.IsValid() {
-			log.Error(c.ctx, "invalid declaration position", err, tag.Of("Label", item.Label))
 			goto Return
 		}
 		uri := span.FileURI(pos.Filename)
 		f, err := c.view.GetFile(c.ctx, uri)
 		if err != nil {
-			log.Error(c.ctx, "unable to get file", err, tag.Of("URI", uri))
 			goto Return
 		}
 		gof, ok := f.(GoFile)
 		if !ok {
-			log.Error(c.ctx, "declaration in a Go file", err, tag.Of("Label", item.Label))
 			goto Return
 		}
-		ident, err := Identifier(c.ctx, gof, declRange.Start)
+		pkg, err := gof.GetCachedPackage(c.ctx)
+		if err != nil {
+			goto Return
+		}
+		var file *ast.File
+		for _, ph := range pkg.GetHandles() {
+			if ph.File().Identity().URI == gof.URI() {
+				file, _ = ph.Cached(c.ctx)
+			}
+		}
+		if file == nil {
+			goto Return
+		}
+		ident, err := findIdentifier(c.ctx, gof, pkg, file, declRange.Start)
 		if err != nil {
-			log.Error(c.ctx, "no identifier", err, tag.Of("Name", obj.Name()))
 			goto Return
 		}
 		documentation, err := ident.Documentation(c.ctx, SynopsisDocumentation)
 		if err != nil {
-			log.Error(c.ctx, "no documentation", err, tag.Of("Name", obj.Name()))
 			goto Return
 		}
 		item.Documentation = documentation
diff --git a/internal/lsp/source/diagnostics.go b/internal/lsp/source/diagnostics.go
index 51cc41dbcc..0d9bf9d15f 100644
--- a/internal/lsp/source/diagnostics.go
+++ b/internal/lsp/source/diagnostics.go
@@ -70,8 +70,8 @@ func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[
 	}
 	// Prepare the reports we will send for the files in this package.
 	reports := make(map[span.URI][]Diagnostic)
-	for _, filename := range pkg.GetFilenames() {
-		clearReports(view, reports, span.FileURI(filename))
+	for _, fh := range pkg.GetHandles() {
+		clearReports(view, reports, fh.File().Identity().URI)
 	}
 
 	// Prepare any additional reports for the errors in this package.
@@ -96,8 +96,8 @@ func Diagnostics(ctx context.Context, view View, f GoFile, disabledAnalyses map[
 		if pkg == nil {
 			continue
 		}
-		for _, filename := range pkg.GetFilenames() {
-			clearReports(view, reports, span.FileURI(filename))
+		for _, fh := range pkg.GetHandles() {
+			clearReports(view, reports, fh.File().Identity().URI)
 		}
 		diagnostics(ctx, view, pkg, reports)
 	}
diff --git a/internal/lsp/source/identifier.go b/internal/lsp/source/identifier.go
index 42bb93bb75..0df7cf6fa2 100644
--- a/internal/lsp/source/identifier.go
+++ b/internal/lsp/source/identifier.go
@@ -48,14 +48,22 @@ func (i *IdentifierInfo) DeclarationRange() span.Range {
 // Identifier returns identifier information for a position
 // in a file, accounting for a potentially incomplete selector.
 func Identifier(ctx context.Context, f GoFile, pos token.Pos) (*IdentifierInfo, error) {
-	file, err := f.GetAST(ctx, ParseFull)
-	if file == nil {
-		return nil, err
-	}
 	pkg := f.GetPackage(ctx)
 	if pkg == nil || pkg.IsIllTyped() {
 		return nil, errors.Errorf("pkg for %s is ill-typed", f.URI())
 	}
+	var (
+		file *ast.File
+		err  error
+	)
+	for _, ph := range pkg.GetHandles() {
+		if ph.File().Identity().URI == f.URI() {
+			file, err = ph.Cached(ctx)
+		}
+	}
+	if file == nil {
+		return nil, err
+	}
 	return findIdentifier(ctx, f, pkg, file, pos)
 }
 
@@ -68,7 +76,7 @@ func findIdentifier(ctx context.Context, f GoFile, pkg Package, file *ast.File,
 	// requesting a completion), use the path to the preceding node.
 	result, err := identifier(ctx, f, pkg, file, pos-1)
 	if result == nil && err == nil {
-		err = errors.Errorf("no identifier found")
+		err = errors.Errorf("no identifier found for %s", f.FileSet().Position(pos))
 	}
 	return result, err
 }
@@ -238,13 +246,16 @@ func objToNode(ctx context.Context, view View, originPkg *types.Package, obj typ
 	if !ok {
 		return nil, errors.Errorf("%s is not a Go file", s.URI())
 	}
-	// If the object is exported from a different package,
-	// we don't need its full AST to find the definition.
-	mode := ParseFull
-	if obj.Exported() && obj.Pkg() != originPkg {
-		mode = ParseExported
+	declPkg, err := declFile.GetCachedPackage(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var declAST *ast.File
+	for _, ph := range declPkg.GetHandles() {
+		if ph.File().Identity().URI == f.URI() {
+			declAST, err = ph.Cached(ctx)
+		}
 	}
-	declAST, err := declFile.GetAST(ctx, mode)
 	if declAST == nil {
 		return nil, err
 	}
diff --git a/internal/lsp/source/source_test.go b/internal/lsp/source/source_test.go
index 8da36c9852..b6ce7d5b4d 100644
--- a/internal/lsp/source/source_test.go
+++ b/internal/lsp/source/source_test.go
@@ -156,7 +156,8 @@ func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests
 		}
 		pos := tok.Pos(src.Start().Offset())
 		list, surrounding, err := source.Completion(ctx, r.view, f.(source.GoFile), pos, source.CompletionOptions{
-			DeepComplete: strings.Contains(string(src.URI()), "deepcomplete"),
+			DeepComplete:     strings.Contains(string(src.URI()), "deepcomplete"),
+			WantDocumentaton: true,
 		})
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
@@ -273,6 +274,11 @@ func diffCompletionItems(t *testing.T, spn span.Span, want []source.CompletionIt
 		if w.Detail != g.Detail {
 			return summarizeCompletionItems(i, want, got, "incorrect Detail got %v want %v", g.Detail, w.Detail)
 		}
+		if w.Documentation != "" && !strings.HasPrefix(w.Documentation, "@") {
+			if w.Documentation != g.Documentation {
+				return summarizeCompletionItems(i, want, got, "incorrect Documentation got %v want %v", g.Documentation, w.Documentation)
+			}
+		}
 		if w.Kind != g.Kind {
 			return summarizeCompletionItems(i, want, got, "incorrect Kind got %v want %v", g.Kind, w.Kind)
 		}
diff --git a/internal/lsp/source/view.go b/internal/lsp/source/view.go
index 826921e8fd..c66f104329 100644
--- a/internal/lsp/source/view.go
+++ b/internal/lsp/source/view.go
@@ -78,6 +78,9 @@ type ParseGoHandle interface {
 	// Parse returns the parsed AST for the file.
 	// If the file is not available, returns nil and an error.
 	Parse(ctx context.Context) (*ast.File, error)
+
+	// Cached returns the AST for this handle, if it has already been stored.
+	Cached(ctx context.Context) (*ast.File, error)
 }
 
 // ParseMode controls the content of the AST produced when parsing a source file.
@@ -118,10 +121,10 @@ type Cache interface {
 	FileSet() *token.FileSet
 
 	// Token returns a TokenHandle for the given file handle.
-	TokenHandle(FileHandle) TokenHandle
+	TokenHandle(fh FileHandle) TokenHandle
 
 	// ParseGo returns a ParseGoHandle for the given file handle.
-	ParseGoHandle(FileHandle, ParseMode) ParseGoHandle
+	ParseGoHandle(fh FileHandle, mode ParseMode) ParseGoHandle
 }
 
 // Session represents a single connection from a client.
@@ -228,9 +231,12 @@ type File interface {
 type GoFile interface {
 	File
 
-	// GetAST returns the full AST for the file.
+	// GetAST returns the AST for the file, at or above the given mode.
 	GetAST(ctx context.Context, mode ParseMode) (*ast.File, error)
 
+	// GetCachedPackage returns the cached package for the file, if any.
+	GetCachedPackage(ctx context.Context) (Package, error)
+
 	// GetPackage returns the package that this file belongs to.
 	GetPackage(ctx context.Context) Package
 
@@ -255,7 +261,7 @@ type SumFile interface {
 type Package interface {
 	ID() string
 	PkgPath() string
-	GetFilenames() []string
+	GetHandles() []ParseGoHandle
 	GetSyntax(context.Context) []*ast.File
 	GetErrors() []packages.Error
 	GetTypes() *types.Package
diff --git a/internal/lsp/testdata/bar/bar.go.in b/internal/lsp/testdata/bar/bar.go.in
index c53facf03e..67df955646 100644
--- a/internal/lsp/testdata/bar/bar.go.in
+++ b/internal/lsp/testdata/bar/bar.go.in
@@ -13,7 +13,8 @@ func _() {
 	_ = foo.StructFoo{} //@complete("S", Foo, IntFoo, StructFoo)
 }
 
-func Bar() { //@item(Bar, "Bar", "func()", "func")
+// Bar is a function.
+func Bar() { //@item(Bar, "Bar", "func()", "func", "Bar is a function.")
 	foo.Foo()        //@complete("F", Foo, IntFoo, StructFoo)
 	var _ foo.IntFoo //@complete("I", Foo, IntFoo, StructFoo)
 	foo.()           //@complete("(", Foo, IntFoo, StructFoo)
diff --git a/internal/lsp/testdata/deepcomplete/deep_complete.go b/internal/lsp/testdata/deepcomplete/deep_complete.go
index 970ec65788..bfde660554 100644
--- a/internal/lsp/testdata/deepcomplete/deep_complete.go
+++ b/internal/lsp/testdata/deepcomplete/deep_complete.go
@@ -26,9 +26,9 @@ func _() {
 func wantsContext(context.Context) {}
 
 func _() {
-	context.Background() //@item(ctxBackground, "context.Background", "func() context.Context", "func")
-	context.TODO()       //@item(ctxTODO, "context.TODO", "func() context.Context", "func")
-	/* context.WithValue(parent context.Context, key interface{}, val interface{}) */ //@item(ctxWithValue, "context.WithValue", "func(parent context.Context, key interface{}, val interface{}) context.Context", "func")
+	context.Background()             //@item(ctxBackground, "context.Background", "func() context.Context", "func", "Background returns a non-nil, empty Context.")
+	context.TODO()                   //@item(ctxTODO, "context.TODO", "func() context.Context", "func", "TODO returns a non-nil, empty Context.")
+	context.WithValue(nil, nil, nil) //@item(ctxWithValue, "context.WithValue", "func(parent context.Context, key interface{}, val interface{}) context.Context", "func", "WithValue returns a copy of parent in which the value associated with key is val.")
 
 	wantsContext(c) //@complete(")", ctxBackground, ctxTODO, ctxWithValue, ctxPackage)
 }
diff --git a/internal/lsp/tests/tests.go b/internal/lsp/tests/tests.go
index 73063c833f..88fb2c36ef 100644
--- a/internal/lsp/tests/tests.go
+++ b/internal/lsp/tests/tests.go
@@ -208,7 +208,7 @@ func Load(t testing.TB, exporter packagestest.Exporter, dir string) *Data {
 
 	// Do a first pass to collect special markers for completion.
 	if err := data.Exported.Expect(map[string]interface{}{
-		"item": func(name string, r packagestest.Range, _, _ string) {
+		"item": func(name string, r packagestest.Range, _ []string) {
 			data.Exported.Mark(name, r)
 		},
 	}); err != nil {
@@ -437,11 +437,20 @@ func (data *Data) collectCompletions(src span.Span, expected []token.Pos) {
 	data.Completions[src] = expected
 }
 
-func (data *Data) collectCompletionItems(pos token.Pos, label, detail, kind string) {
+func (data *Data) collectCompletionItems(pos token.Pos, args []string) {
+	if len(args) < 3 {
+		return
+	}
+	label, detail, kind := args[0], args[1], args[2]
+	var documentation string
+	if len(args) == 4 {
+		documentation = args[3]
+	}
 	data.CompletionItems[pos] = &source.CompletionItem{
-		Label:  label,
-		Detail: detail,
-		Kind:   source.ParseCompletionItemKind(kind),
+		Label:         label,
+		Detail:        detail,
+		Kind:          source.ParseCompletionItemKind(kind),
+		Documentation: documentation,
 	}
 }
 
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index 68abec0eb9..14a823b150 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -169,13 +169,13 @@ func (s *Server) didClose(ctx context.Context, params *protocol.DidCloseTextDocu
 		log.Error(ctx, "no package available", nil, telemetry.File)
 		return nil
 	}
-	for _, filename := range pkg.GetFilenames() {
+	for _, ph := range pkg.GetHandles() {
 		// If other files from this package are open, don't clear.
-		if s.session.IsOpen(span.NewURI(filename)) {
+		if s.session.IsOpen(ph.File().Identity().URI) {
 			clear = nil
 			return nil
 		}
-		clear = append(clear, span.FileURI(filename))
+		clear = append(clear, ph.File().Identity().URI)
 	}
 	return nil
 }