docs: add comprehensive README with installation and usage guide

Add complete documentation including:
- Feature overview
- cargo install from git instructions
- CLI usage examples with JSON output
- MCP server usage
- Rust library examples with Tool builder
- Python bindings examples
- Response fields reference table
- Error handling documentation
- Configuration options (timeouts, binary detection, HTML conversion)

Author: claude

README.md

@@ -1,2 +1,204 @@
 # webfetch
-AI-friendly webfetch tool, cli, mcp server, and lib
+
+AI-friendly web content fetching tool designed for LLM consumption. Rust library with CLI, MCP server, and Python bindings.
+
+## Features
+
+- **HTTP fetching** - GET and HEAD methods with streaming support
+- **HTML-to-Markdown** - Built-in conversion optimized for LLMs
+- **HTML-to-Text** - Plain text extraction with clean formatting
+- **Binary detection** - Returns metadata only for images, PDFs, etc.
+- **Timeout handling** - 1s first-byte, 30s body with partial content on timeout
+- **URL filtering** - Allow/block lists for controlled access
+- **MCP server** - Model Context Protocol support for AI tool integration
+
+## Installation
+
+### From Git (recommended)
+
+```bash
+cargo install --git https://github.com/anthropics/webfetch webfetch-cli
+```
+
+### From Source
+
+```bash
+git clone https://github.com/anthropics/webfetch
+cd webfetch
+cargo install --path crates/webfetch-cli
+```
+
+## CLI Usage
+
+```bash
+# Basic fetch
+webfetch --url https://example.com
+
+# Convert to markdown
+webfetch --url https://example.com --as-markdown
+
+# Convert to plain text
+webfetch --url https://example.com --as-text
+
+# HEAD request (metadata only)
+webfetch --url https://example.com --method HEAD
+
+# Custom user agent
+webfetch --url https://example.com --user-agent "MyBot/1.0"
+
+# Show full documentation
+webfetch --llmtxt
+```
+
+Output is JSON to stdout:
+
+```json
+{
+  "url": "https://example.com",
+  "status_code": 200,
+  "content_type": "text/html",
+  "size": 1256,
+  "format": "markdown",
+  "content": "# Example Domain\n\nThis domain is for use in illustrative examples...",
+  "truncated": false,
+  "method": "GET"
+}
+```
+
+## MCP Server
+
+Run as a Model Context Protocol server:
+
+```bash
+webfetch mcp
+```
+
+Exposes `webfetch` as a tool over JSON-RPC 2.0 stdio transport. Compatible with Claude Desktop and other MCP clients.
+
+## Library Usage
+
+Add to `Cargo.toml`:
+
+```toml
+[dependencies]
+webfetch = { git = "https://github.com/anthropics/webfetch" }
+```
+
+### Basic Fetch
+
+```rust
+use webfetch::{fetch, WebFetchRequest};
+
+#[tokio::main]
+async fn main() {
+    let request = WebFetchRequest {
+        url: "https://example.com".to_string(),
+        method: None,
+        as_markdown: Some(true),
+        as_text: None,
+    };
+
+    let response = fetch(request).await;
+    println!("{}", response.content.unwrap_or_default());
+}
+```
+
+### With Tool Builder
+
+```rust
+use webfetch::Tool;
+
+let tool = Tool::builder()
+    .enable_markdown(true)
+    .enable_text(false)
+    .user_agent("MyBot/1.0")
+    .allow_prefix("https://docs.example.com")
+    .block_prefix("https://internal.example.com")
+    .build();
+
+let response = tool.fetch(request).await;
+```
+
+## Python Bindings
+
+```bash
+pip install webfetch
+```
+
+```python
+from webfetch import fetch, WebFetchRequest, WebFetchTool
+
+# Simple fetch
+response = fetch("https://example.com", as_markdown=True)
+print(response.content)
+
+# With configuration
+tool = WebFetchTool(
+    enable_markdown=True,
+    user_agent="MyBot/1.0",
+    allow_prefixes=["https://docs.example.com"]
+)
+response = tool.fetch(WebFetchRequest(url="https://example.com"))
+```
+
+## Response Fields
+
+| Field | Type | Description |
+|-------|------|-------------|
+| `url` | string | Fetched URL |
+| `status_code` | int | HTTP status code |
+| `content_type` | string? | Content-Type header |
+| `size` | int? | Content size in bytes |
+| `last_modified` | string? | Last-Modified header |
+| `filename` | string? | From Content-Disposition |
+| `format` | string | "markdown", "text", or "raw" |
+| `content` | string? | Page content |
+| `truncated` | bool | True if content was cut off |
+| `method` | string | HTTP method used |
+| `error` | string? | Error message if failed |
+
+## Error Handling
+
+Errors are returned in the `error` field:
+
+- `InvalidUrl` - Malformed URL
+- `UrlBlocked` - URL blocked by filter
+- `NetworkError` - Connection failed
+- `Timeout` - Request timed out
+- `HttpError` - 4xx/5xx response
+- `ContentError` - Failed to read body
+- `BinaryContent` - Binary content not supported
+
+## Configuration
+
+### Timeouts
+
+- **First-byte**: 1 second (connect + initial response)
+- **Body**: 30 seconds total
+
+Partial content is returned on body timeout with `truncated: true`.
+
+### Binary Content
+
+Automatically detected and returns metadata only for:
+- Images, audio, video, fonts
+- PDFs, archives (zip, tar, rar, 7z)
+- Office documents
+
+### HTML Conversion
+
+**Markdown mode** (`--as-markdown`):
+- Headers: `h1-h6` → `#` to `######`
+- Lists: Proper nesting with 2-space indent
+- Code: Fenced blocks and inline backticks
+- Links: `[text](url)` format
+- Strips: scripts, styles, iframes, SVGs
+
+**Text mode** (`--as-text`):
+- Plain text extraction
+- Normalized whitespace
+- Newlines for block elements
+
+## License
+
+MIT