v0.0.3: add built-in web tools

Add no-key web_search and web_fetch tools.
Fetch pages with net/http and parse HTML content.
Document built-in web capabilities.

README.md

@@ -11,6 +11,7 @@ model/provider switching, and local tools.
 - Multiple providers from `~/.agentu/config.yaml`.
 - Session-only provider, model, and thinking-level switching.
 - Read-only project tools enabled by default.
+- Built-in web search and URL fetching.
 - `--yolo` mode for file writes and shell execution.
 
 ## Quick Start
@@ -58,6 +59,10 @@ agent:
   tool_timeout: 30s
 ```
 
+Web tools are enabled by default with a built-in no-key backend. agentu exposes
+`web_search` for current or external web information and `web_fetch` for reading
+a known URL.
+
 Provider names are the keys under `providers`. At startup, agentu selects the
 first provider by name. Use `/model provider <name>` to switch providers for the
 current session.
@@ -112,6 +117,11 @@ Read-only tools are available by default:
 - `file_list`
 - `file_search`
 
+Web tools are also available in read-only mode:
+
+- `web_search`
+- `web_fetch`
+
 `--yolo` additionally enables:
 
 - `file_write`

cmd/agentu/main.go

@@ -60,6 +60,8 @@ func run() error {
 	} else {
 		registry = tools.ReadOnlyBuiltins(cfg.Agent.WorkingDir)
 	}
+	registry.Register(tools.NewBuiltinSearchTool(http.DefaultClient))
+	registry.Register(tools.NewBuiltinFetchTool(http.DefaultClient))
 	systemPrompt := strings.TrimSpace(cfg.Agent.SystemPrompt + "\n\n" + tools.AgentInstructions(cfg.Agent.WorkingDir, *yolo))
 
 	assistant := agent.New(agent.Options{

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/glamour v1.0.0
 	github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834
+	golang.org/x/net v0.38.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -39,7 +40,6 @@ require (
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
 	github.com/yuin/goldmark v1.7.13 // indirect
 	github.com/yuin/goldmark-emoji v1.0.6 // indirect
-	golang.org/x/net v0.38.0 // indirect
 	golang.org/x/sys v0.38.0 // indirect
 	golang.org/x/term v0.36.0 // indirect
 	golang.org/x/text v0.30.0 // indirect

internal/tools/tools.go

@@ -82,6 +82,9 @@ func Builtins(workingDir string) *Registry {
 }
 
 func AgentInstructions(workingDir string, yolo bool) string {
+	searchInstructions := webSearchInstructions()
+	readOnlyTools := "file_list, file_read, file_search, web_search, web_fetch"
+	yoloTools := "file_list, file_read, file_search, file_write, shell_run, web_search, web_fetch"
 	if yolo {
 		return fmt.Sprintf(`Local project context:
 - The project working directory is %q.
@@ -92,8 +95,9 @@ func AgentInstructions(workingDir string, yolo bool) string {
 - When the user asks to run, execute, test, check, debug, or inspect a shell command, use shell_run. This includes local commands written in backticks, such as go, make, git, pwd, ls, ps, and similar terminal commands.
 - Do not use file tools as a substitute for a command execution request.
 - Do not start interactive or long-running sessions. Prefer bounded, non-interactive local commands with clear completion conditions.
+- %s
 - Tool paths should normally be relative to the project working directory.
-- Available tools: file_list, file_read, file_search, file_write, shell_run.`, workingDir)
+- Available tools: %s.`, workingDir, searchInstructions, yoloTools)
 	}
 	return fmt.Sprintf(`Local project context:
 - The project working directory is %q.
@@ -102,8 +106,13 @@ func AgentInstructions(workingDir string, yolo bool) string {
 - Do not explore the project preemptively. Do not call file_list just to discover context unless the user asks about project files or the answer truly depends on local files.
 - When the user asks to inspect, list, search, or read project files, use file_list, file_search, and file_read instead of saying you cannot access local files.
 - Shell command execution is disabled in this mode. When the user asks to run, execute, test, check, debug, or inspect a shell command, do not use file tools as a substitute; explain that they need to restart agentu with --yolo to enable shell_run.
+- %s
 - Tool paths should normally be relative to the project working directory.
-- Available tools: file_list, file_read, file_search.`, workingDir)
+- Available tools: %s.`, workingDir, searchInstructions, readOnlyTools)
+}
+
+func webSearchInstructions() string {
+	return "When the user's request depends on current or external web information, use web_search. This includes news, prices, laws, schedules, software versions, product recommendations, or requests for the latest information. Use web_fetch to read a source URL when search snippets are not enough, when the user provides a URL, or when the user names a specific website to inspect. Base answers on returned sources and include source URLs when useful."
 }
 
 func JSONSchema(schema string) json.RawMessage {

internal/tools/tools_test.go

@@ -84,6 +84,27 @@ func TestReadOnlyBuiltinsExposeOpenAICompatibleNamesAndAliases(t *testing.T) {
 	}
 }
 
+func TestRegistryCanExposeWebSearch(t *testing.T) {
+	registry := ReadOnlyBuiltins(t.TempDir())
+	registry.Register(NewBuiltinSearchTool(nil))
+	registry.Register(NewBuiltinFetchTool(nil))
+
+	var names []string
+	for _, def := range registry.Definitions() {
+		names = append(names, def.Function.Name)
+	}
+	for _, want := range []string{"web_search", "web_fetch"} {
+		if !slices.Contains(names, want) {
+			t.Fatalf("definitions missing %s: %#v", want, names)
+		}
+	}
+	for _, want := range []string{"web_search", "web_fetch"} {
+		if _, ok := registry.Get(want); !ok {
+			t.Fatalf("%s missing", want)
+		}
+	}
+}
+
 func TestBuiltinsExposeYoloTools(t *testing.T) {
 	registry := Builtins(t.TempDir())
 	for _, name := range []string{"file_write", "shell_run", "file.write", "shell.run"} {
@@ -108,3 +129,12 @@ func TestAgentInstructionsExplainCommandModes(t *testing.T) {
 		}
 	}
 }
+
+func TestAgentInstructionsExplainWebSearch(t *testing.T) {
+	withSearch := AgentInstructions("/tmp/project", false)
+	for _, want := range []string{"use web_search", "Use web_fetch", "latest information", "source URLs", "Available tools: file_list, file_read, file_search, web_search, web_fetch"} {
+		if !strings.Contains(withSearch, want) {
+			t.Fatalf("web search instructions missing %q:\n%s", want, withSearch)
+		}
+	}
+}

internal/tools/web_builtin.go

@@ -0,0 +1,597 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"agentu/internal/llm"
+
+	"golang.org/x/net/html"
+)
+
+const (
+	defaultSearchBaseURL = "https://html.duckduckgo.com/html/"
+	defaultUserAgent     = "agentu/0.0.3"
+	maxSearchResults     = 20
+	maxWebReadBytes      = 2 * 1024 * 1024
+)
+
+type BuiltinSearchTool struct {
+	baseURL    string
+	maxResults int
+	client     *http.Client
+}
+
+func NewBuiltinSearchTool(client *http.Client) *BuiltinSearchTool {
+	return NewBuiltinSearchToolWithBaseURL(defaultSearchBaseURL, 5, client)
+}
+
+func NewBuiltinSearchToolWithBaseURL(baseURL string, maxResults int, client *http.Client) *BuiltinSearchTool {
+	if strings.TrimSpace(baseURL) == "" {
+		baseURL = defaultSearchBaseURL
+	}
+	if maxResults <= 0 {
+		maxResults = 5
+	}
+	if client == nil {
+		client = http.DefaultClient
+	}
+	return &BuiltinSearchTool{
+		baseURL:    baseURL,
+		maxResults: maxResults,
+		client:     client,
+	}
+}
+
+func (t *BuiltinSearchTool) Definition() llm.Tool {
+	return webSearchDefinition()
+}
+
+func webSearchDefinition() llm.Tool {
+	return llm.Tool{
+		Type: "function",
+		Function: llm.ToolFunction{
+			Name:        "web_search",
+			Description: "Search the public web for current or external information. Use for recent facts, news, prices, schedules, versions, policies, recommendations, or other questions that need online sources. Results include source URLs.",
+			Parameters: JSONSchema(`{
+  "type": "object",
+  "properties": {
+    "query": {"type": "string", "description": "Search query."},
+    "max_results": {"type": "integer", "description": "Optional result count from 1 to 20. Defaults to 5.", "minimum": 1, "maximum": 20},
+    "topic": {"type": "string", "description": "Optional topic hint. Accepted for compatibility but the built-in backend may ignore it.", "enum": ["general", "news", "finance"]}
+  },
+  "required": ["query"],
+  "additionalProperties": false
+}`),
+		},
+	}
+}
+
+func (t *BuiltinSearchTool) Execute(ctx context.Context, raw json.RawMessage) (string, error) {
+	args, err := parseWebSearchArgs(raw, t.maxResults)
+	if err != nil {
+		return "", err
+	}
+
+	endpoint, err := url.Parse(t.baseURL)
+	if err != nil {
+		return "", fmt.Errorf("parse search endpoint: %w", err)
+	}
+	query := endpoint.Query()
+	query.Set("q", args.Query)
+	endpoint.RawQuery = query.Encode()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint.String(), nil)
+	if err != nil {
+		return "", fmt.Errorf("create search request: %w", err)
+	}
+	req.Header.Set("User-Agent", defaultUserAgent)
+	req.Header.Set("Accept", "text/html,application/xhtml+xml")
+
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("search request: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		body, _ := io.ReadAll(io.LimitReader(resp.Body, 8*1024))
+		return "", fmt.Errorf("web search failed: status %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
+	}
+
+	results, err := parseSearchResults(resp.Body, args.MaxResults)
+	if err != nil {
+		return "", err
+	}
+	return FormatResult(formatWebSearchResults(args.Query, "", results)), nil
+}
+
+type BuiltinFetchTool struct {
+	client *http.Client
+}
+
+type webSearchArgs struct {
+	Query      string `json:"query"`
+	MaxResults int    `json:"max_results"`
+	Topic      string `json:"topic"`
+}
+
+type webSearchResult struct {
+	Title   string  `json:"title"`
+	URL     string  `json:"url"`
+	Content string  `json:"content"`
+	Score   float64 `json:"score"`
+}
+
+type webFetchArgs struct {
+	URL   string `json:"url"`
+	Query string `json:"query"`
+}
+
+type webFetchResponse struct {
+	Results       []webFetchResult `json:"results"`
+	FailedResults []webFetchFailed `json:"failed_results"`
+}
+
+type webFetchResult struct {
+	URL        string `json:"url"`
+	RawContent string `json:"raw_content"`
+}
+
+type webFetchFailed struct {
+	URL   string `json:"url"`
+	Error string `json:"error"`
+}
+
+func NewBuiltinFetchTool(client *http.Client) *BuiltinFetchTool {
+	if client == nil {
+		client = http.DefaultClient
+	}
+	return &BuiltinFetchTool{client: client}
+}
+
+func (t *BuiltinFetchTool) Definition() llm.Tool {
+	return webFetchDefinition()
+}
+
+func webFetchDefinition() llm.Tool {
+	return llm.Tool{
+		Type: "function",
+		Function: llm.ToolFunction{
+			Name:        "web_fetch",
+			Description: "Fetch and extract readable Markdown content from a public web URL. Use after web_search when snippets are not enough, or when the user gives a URL or website to inspect. Results include the source URL.",
+			Parameters: JSONSchema(`{
+  "type": "object",
+  "properties": {
+    "url": {"type": "string", "description": "Public http or https URL to fetch. URLs without a scheme are treated as https URLs."},
+    "query": {"type": "string", "description": "Optional extraction focus. Accepted for compatibility but the built-in backend may ignore it."}
+  },
+  "required": ["url"],
+  "additionalProperties": false
+}`),
+		},
+	}
+}
+
+func (t *BuiltinFetchTool) Execute(ctx context.Context, raw json.RawMessage) (string, error) {
+	args, err := parseWebFetchArgs(raw)
+	if err != nil {
+		return "", err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, args.URL, nil)
+	if err != nil {
+		return "", fmt.Errorf("create fetch request: %w", err)
+	}
+	req.Header.Set("User-Agent", defaultUserAgent)
+	req.Header.Set("Accept", "text/html,text/plain,application/xhtml+xml")
+
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("fetch request: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		body, _ := io.ReadAll(io.LimitReader(resp.Body, 8*1024))
+		return "", fmt.Errorf("web fetch failed: status %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
+	}
+
+	data, err := io.ReadAll(io.LimitReader(resp.Body, maxWebReadBytes))
+	if err != nil {
+		return "", fmt.Errorf("read response: %w", err)
+	}
+	contentType := strings.ToLower(resp.Header.Get("Content-Type"))
+	var content string
+	if strings.Contains(contentType, "html") || contentType == "" {
+		content, err = htmlToMarkdown(string(data), args.URL)
+		if err != nil {
+			return "", err
+		}
+	} else if strings.Contains(contentType, "text/plain") || strings.Contains(contentType, "markdown") {
+		content = strings.TrimSpace(string(data))
+	} else {
+		return "", fmt.Errorf("unsupported content type: %s", contentType)
+	}
+
+	result := webFetchResponse{
+		Results: []webFetchResult{{
+			URL:        args.URL,
+			RawContent: content,
+		}},
+	}
+	return FormatResult(formatWebFetchResults(args.URL, result)), nil
+}
+
+func parseWebSearchArgs(raw json.RawMessage, defaultMaxResults int) (webSearchArgs, error) {
+	var args webSearchArgs
+	if err := json.Unmarshal(raw, &args); err != nil {
+		return args, fmt.Errorf("parse arguments: %w", err)
+	}
+	args.Query = strings.TrimSpace(args.Query)
+	if args.Query == "" {
+		return args, errors.New("query is required")
+	}
+	if args.MaxResults == 0 {
+		args.MaxResults = defaultMaxResults
+	}
+	if args.MaxResults < 1 || args.MaxResults > maxSearchResults {
+		return args, fmt.Errorf("max_results must be between 1 and %d", maxSearchResults)
+	}
+	args.Topic = strings.ToLower(strings.TrimSpace(args.Topic))
+	if args.Topic == "" {
+		args.Topic = "general"
+	}
+	switch args.Topic {
+	case "general", "news", "finance":
+	default:
+		return args, fmt.Errorf("topic must be one of: general, news, finance")
+	}
+	return args, nil
+}
+
+func parseWebFetchArgs(raw json.RawMessage) (webFetchArgs, error) {
+	var args webFetchArgs
+	if err := json.Unmarshal(raw, &args); err != nil {
+		return args, fmt.Errorf("parse arguments: %w", err)
+	}
+	args.URL = strings.TrimSpace(args.URL)
+	if args.URL == "" {
+		return args, errors.New("url is required")
+	}
+	if !strings.Contains(args.URL, "://") {
+		args.URL = "https://" + args.URL
+	}
+	parsed, err := url.Parse(args.URL)
+	if err != nil || (parsed.Scheme != "http" && parsed.Scheme != "https") || parsed.Host == "" {
+		return args, errors.New("url must be a valid http or https URL")
+	}
+	args.Query = strings.TrimSpace(args.Query)
+	return args, nil
+}
+
+func formatWebSearchResults(query string, answer string, results []webSearchResult) string {
+	if len(results) == 0 {
+		return fmt.Sprintf("No web search results for %q.", query)
+	}
+
+	var b strings.Builder
+	fmt.Fprintf(&b, "Web search results for %q:\n", query)
+	if strings.TrimSpace(answer) != "" {
+		fmt.Fprintf(&b, "\nSummary: %s\n", strings.TrimSpace(answer))
+	}
+	for i, result := range results {
+		title := strings.TrimSpace(result.Title)
+		if title == "" {
+			title = "Untitled"
+		}
+		fmt.Fprintf(&b, "\n%d. %s\n", i+1, title)
+		fmt.Fprintf(&b, "   Source: %s\n", strings.TrimSpace(result.URL))
+		if content := strings.TrimSpace(result.Content); content != "" {
+			fmt.Fprintf(&b, "   Snippet: %s\n", content)
+		}
+		if result.Score > 0 {
+			fmt.Fprintf(&b, "   Score: %.3f\n", result.Score)
+		}
+	}
+	return strings.TrimRight(b.String(), "\n")
+}
+
+func formatWebFetchResults(inputURL string, response webFetchResponse) string {
+	var b strings.Builder
+	if len(response.Results) == 0 {
+		fmt.Fprintf(&b, "No readable web content extracted from %s.", inputURL)
+	} else {
+		fmt.Fprintf(&b, "Fetched web content:\n")
+		for i, result := range response.Results {
+			sourceURL := strings.TrimSpace(result.URL)
+			if sourceURL == "" {
+				sourceURL = inputURL
+			}
+			fmt.Fprintf(&b, "\n%d. Source: %s\n", i+1, sourceURL)
+			if content := strings.TrimSpace(result.RawContent); content != "" {
+				fmt.Fprintf(&b, "\n%s\n", content)
+			}
+		}
+	}
+	for _, failed := range response.FailedResults {
+		sourceURL := strings.TrimSpace(failed.URL)
+		if sourceURL == "" {
+			sourceURL = inputURL
+		}
+		if strings.TrimSpace(failed.Error) != "" {
+			fmt.Fprintf(&b, "\nFetch failed for %s: %s", sourceURL, strings.TrimSpace(failed.Error))
+		}
+	}
+	return strings.TrimRight(b.String(), "\n")
+}
+
+func parseSearchResults(r io.Reader, maxResults int) ([]webSearchResult, error) {
+	doc, err := html.Parse(r)
+	if err != nil {
+		return nil, fmt.Errorf("parse search results: %w", err)
+	}
+
+	results := make([]webSearchResult, 0, maxResults)
+	var walk func(*html.Node)
+	walk = func(n *html.Node) {
+		if len(results) >= maxResults || n == nil {
+			return
+		}
+		if n.Type == html.ElementNode && n.Data == "div" && hasClass(n, "result") {
+			if result, ok := parseResultNode(n); ok {
+				results = append(results, result)
+			}
+			return
+		}
+		for child := n.FirstChild; child != nil; child = child.NextSibling {
+			walk(child)
+		}
+	}
+	walk(doc)
+	return results, nil
+}
+
+func parseResultNode(n *html.Node) (webSearchResult, bool) {
+	var result webSearchResult
+	var walk func(*html.Node)
+	walk = func(node *html.Node) {
+		if node == nil {
+			return
+		}
+		if node.Type == html.ElementNode && node.Data == "a" {
+			if hasClass(node, "result__a") && result.URL == "" {
+				result.Title = cleanWebText(textContent(node))
+				result.URL = decodeSearchURL(attr(node, "href"))
+			}
+			if hasClass(node, "result__snippet") && result.Content == "" {
+				result.Content = cleanWebText(textContent(node))
+			}
+		}
+		if node.Type == html.ElementNode && (node.Data == "div" || node.Data == "span") && hasClass(node, "result__snippet") && result.Content == "" {
+			result.Content = cleanWebText(textContent(node))
+		}
+		for child := node.FirstChild; child != nil; child = child.NextSibling {
+			walk(child)
+		}
+	}
+	walk(n)
+	return result, result.Title != "" && result.URL != ""
+}
+
+func decodeSearchURL(raw string) string {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return ""
+	}
+	parsed, err := url.Parse(raw)
+	if err == nil {
+		if target := parsed.Query().Get("uddg"); target != "" {
+			if decoded, err := url.QueryUnescape(target); err == nil {
+				return decoded
+			}
+			return target
+		}
+	}
+	return raw
+}
+
+func htmlToMarkdown(input string, sourceURL string) (string, error) {
+	doc, err := html.Parse(strings.NewReader(input))
+	if err != nil {
+		return "", fmt.Errorf("parse html: %w", err)
+	}
+
+	var b strings.Builder
+	var title string
+	var walk func(*html.Node, int)
+	walk = func(n *html.Node, listDepth int) {
+		if n == nil || skipHTMLNode(n) {
+			return
+		}
+		if n.Type == html.ElementNode && n.Data == "title" && title == "" {
+			title = cleanWebText(textContent(n))
+			return
+		}
+		if n.Type == html.TextNode {
+			writeInlineText(&b, n.Data)
+			return
+		}
+		if n.Type != html.ElementNode {
+			for child := n.FirstChild; child != nil; child = child.NextSibling {
+				walk(child, listDepth)
+			}
+			return
+		}
+
+		switch n.Data {
+		case "h1", "h2", "h3", "h4", "h5", "h6":
+			writeBlockBreak(&b)
+			level := int(n.Data[1] - '0')
+			b.WriteString(strings.Repeat("#", level))
+			b.WriteString(" ")
+			writeChildren(&b, n, listDepth, walk)
+			writeBlockBreak(&b)
+		case "p", "div", "section", "article", "header", "footer", "main", "tr":
+			writeBlockBreak(&b)
+			writeChildren(&b, n, listDepth, walk)
+			writeBlockBreak(&b)
+		case "br":
+			b.WriteString("\n")
+		case "li":
+			writeBlockBreak(&b)
+			b.WriteString(strings.Repeat("  ", listDepth))
+			b.WriteString("- ")
+			writeChildren(&b, n, listDepth+1, walk)
+			writeBlockBreak(&b)
+		case "a":
+			label := cleanWebText(textContent(n))
+			href := strings.TrimSpace(attr(n, "href"))
+			if href != "" && label != "" {
+				href = resolveURL(sourceURL, href)
+				b.WriteString(label)
+				b.WriteString(" (")
+				b.WriteString(href)
+				b.WriteString(")")
+				return
+			}
+			writeChildren(&b, n, listDepth, walk)
+		default:
+			writeChildren(&b, n, listDepth, walk)
+		}
+	}
+	walk(doc, 0)
+
+	content := normalizeMarkdownText(b.String())
+	if title != "" && !strings.Contains(content, title) {
+		content = "# " + title + "\n\n" + content
+	}
+	if strings.TrimSpace(content) == "" {
+		return "", errors.New("no readable content found")
+	}
+	return content, nil
+}
+
+func writeChildren(b *strings.Builder, n *html.Node, listDepth int, walk func(*html.Node, int)) {
+	for child := n.FirstChild; child != nil; child = child.NextSibling {
+		walk(child, listDepth)
+	}
+}
+
+func writeInlineText(b *strings.Builder, text string) {
+	text = cleanWebText(text)
+	if text == "" {
+		return
+	}
+	if b.Len() > 0 {
+		last := b.String()[b.Len()-1]
+		if last != '\n' && last != ' ' {
+			b.WriteByte(' ')
+		}
+	}
+	b.WriteString(text)
+}
+
+func writeBlockBreak(b *strings.Builder) {
+	if b.Len() == 0 {
+		return
+	}
+	text := b.String()
+	if strings.HasSuffix(text, "\n\n") {
+		return
+	}
+	if strings.HasSuffix(text, "\n") {
+		b.WriteByte('\n')
+		return
+	}
+	b.WriteString("\n\n")
+}
+
+func skipHTMLNode(n *html.Node) bool {
+	if n.Type != html.ElementNode {
+		return false
+	}
+	switch n.Data {
+	case "script", "style", "noscript", "svg", "canvas", "template":
+		return true
+	default:
+		return false
+	}
+}
+
+func textContent(n *html.Node) string {
+	var b strings.Builder
+	var walk func(*html.Node)
+	walk = func(node *html.Node) {
+		if node == nil || skipHTMLNode(node) {
+			return
+		}
+		if node.Type == html.TextNode {
+			b.WriteString(node.Data)
+			b.WriteByte(' ')
+			return
+		}
+		for child := node.FirstChild; child != nil; child = child.NextSibling {
+			walk(child)
+		}
+	}
+	walk(n)
+	return cleanWebText(b.String())
+}
+
+func hasClass(n *html.Node, class string) bool {
+	for _, item := range strings.Fields(attr(n, "class")) {
+		if item == class {
+			return true
+		}
+	}
+	return false
+}
+
+func attr(n *html.Node, name string) string {
+	for _, item := range n.Attr {
+		if item.Key == name {
+			return item.Val
+		}
+	}
+	return ""
+}
+
+func resolveURL(baseURL, raw string) string {
+	ref, err := url.Parse(raw)
+	if err != nil {
+		return raw
+	}
+	base, err := url.Parse(baseURL)
+	if err != nil {
+		return raw
+	}
+	return base.ResolveReference(ref).String()
+}
+
+func cleanWebText(text string) string {
+	return strings.Join(strings.Fields(text), " ")
+}
+
+func normalizeMarkdownText(text string) string {
+	lines := strings.Split(text, "\n")
+	out := make([]string, 0, len(lines))
+	blank := false
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			if !blank && len(out) > 0 {
+				out = append(out, "")
+			}
+			blank = true
+			continue
+		}
+		out = append(out, line)
+		blank = false
+	}
+	return strings.TrimSpace(strings.Join(out, "\n"))
+}

internal/tools/web_builtin_test.go

@@ -0,0 +1,96 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestBuiltinSearchTool(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			t.Fatalf("method = %s", r.Method)
+		}
+		if got := r.URL.Query().Get("q"); got != "agentu" {
+			t.Fatalf("query = %q", got)
+		}
+		w.Header().Set("Content-Type", "text/html")
+		_, _ = w.Write([]byte(`
+<html><body>
+  <div class="result">
+    <a class="result__a" href="/l/?uddg=https%3A%2F%2Fexample.com%2Fagentu">Agentu release</a>
+    <a class="result__snippet">Agentu adds built-in web tools.</a>
+  </div>
+</body></html>`))
+	}))
+	defer server.Close()
+
+	tool := NewBuiltinSearchToolWithBaseURL(server.URL, 5, server.Client())
+	out, err := tool.Execute(context.Background(), json.RawMessage(`{"query":"agentu"}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{"Web search results", "Agentu release", "https://example.com/agentu", "Agentu adds built-in web tools"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("output missing %q:\n%s", want, out)
+		}
+	}
+}
+
+func TestBuiltinFetchTool(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			t.Fatalf("method = %s", r.Method)
+		}
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		_, _ = w.Write([]byte(`
+<html>
+  <head><title>Agentu</title><script>hidden()</script></head>
+  <body>
+    <h1>Agentu</h1>
+    <p>Built-in fetch reads HTML.</p>
+    <ul><li>Search</li><li>Fetch</li></ul>
+  </body>
+</html>`))
+	}))
+	defer server.Close()
+
+	tool := NewBuiltinFetchTool(server.Client())
+	out, err := tool.Execute(context.Background(), json.RawMessage(`{"url":"`+server.URL+`"}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{"Fetched web content", server.URL, "# Agentu", "Built-in fetch reads HTML", "- Search", "- Fetch"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("output missing %q:\n%s", want, out)
+		}
+	}
+	if strings.Contains(out, "hidden") {
+		t.Fatalf("script content should be ignored:\n%s", out)
+	}
+}
+
+func TestBuiltinFetchToolAcceptsURLsWithoutScheme(t *testing.T) {
+	args, err := parseWebFetchArgs(json.RawMessage(`{"url":"example.com/page"}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if args.URL != "https://example.com/page" {
+		t.Fatalf("url = %q", args.URL)
+	}
+}
+
+func TestBuiltinFetchToolFormatsFailedResults(t *testing.T) {
+	response := webFetchResponse{
+		FailedResults: []webFetchFailed{{URL: "https://example.com", Error: "blocked"}},
+	}
+	out := formatWebFetchResults("https://example.com", response)
+	for _, want := range []string{"No readable web content", "Fetch failed", "blocked"} {
+		if !strings.Contains(out, want) {
+			t.Fatalf("output missing %q:\n%s", want, out)
+		}
+	}
+}