What is duckduckgo-mcp-server CLAUDE.md?

Project instructions for a Python server that lets AI assistants search DuckDuckGo and fetch webpage content. They document the project structure, commands, tests, build process, code checks, and dependency auditing.

Use them when installing dependencies, starting the server, testing its search and webpage-fetching behavior, building the package, checking code quality, or auditing dependencies.

They give an agent the commands and conventions needed to work on, test, build, and run the server correctly.

How nickclyde/duckduckgo-mcp-server configures Claude Code

About the project

duckduckgo-mcp-server is a Model Context Protocol server that lets language-model applications search DuckDuckGo and retrieve and parse webpage content. It is used to give coding agents and other MCP clients web-search and content-fetching capabilities. The catalogue instruction helps configure or use this server.

nickclyde/duckduckgo-mcp-server · 1,568 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to nickclyde/duckduckgo-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/nickclyde/duckduckgo-mcp-server/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/nickclyde/duckduckgo-mcp-server

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/nickclyde/duckduckgo-mcp-server/claude-md/github.svg)](https://agentmods.dev/instructions/nickclyde/duckduckgo-mcp-server/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/nickclyde/duckduckgo-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/nickclyde/duckduckgo-mcp-server/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/nickclyde/duckduckgo-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/nickclyde/duckduckgo-mcp-server/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,548 This file is loaded in full into every session.

When invoked 1,548 The same file — it is already loaded in full.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.01548	$0.01548
Opus 5.5	$0.00619	$0.00619
Sonnet 5.5	$0.00310	$0.00310
Haiku 4.5	$0.00155	$0.00155

Measured 2mo ago against content hash 89ddcbc63d3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

duckduckgo-mcp-server CLAUDE.md scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- `DDG_SEARCH_BACKEND`: `auto` (default) | `httpx` | `curl` — HTTP backend for the search tool. `auto` falls back to curl_cffi Chrome TLS impersonation when DuckDuckGo returns a fingerprint block (HTTP 202/403); `curl`/f

CLAUDE.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

A Model Context Protocol (MCP) server providing DuckDuckGo web search and webpage content fetching. Built with Python on the MCP Python SDK's MCPServer (formerly FastMCP). Published to PyPI as duckduckgo-mcp-server.

Commands

# Install dependencies
uv sync

# Run the server
uv run duckduckgo-mcp-server

# Run with MCP Inspector (for interactive testing)
mcp dev src/duckduckgo_mcp_server/server.py

# Run all tests (unit + e2e)
uv run python -m pytest src/duckduckgo_mcp_server/ -v

# Run only unit tests
uv run python -m pytest src/duckduckgo_mcp_server/test_server.py -v

# Run only e2e MCP protocol tests
uv run python -m pytest src/duckduckgo_mcp_server/test_e2e.py -v

# Run a single test
uv run python -m pytest src/duckduckgo_mcp_server/test_server.py::TestRateLimiter::test_acquire_removes_expired_entries

# Build package
uv build

# Lint (ruff) — matches the CI `quality` job
uv run ruff check .

# Audit dependencies for known vulnerabilities (informational)
uv run --with pip-audit pip-audit --desc

Architecture

Single-module server in src/duckduckgo_mcp_server/server.py with these main classes:

DuckDuckGoSearcher — Scrapes DuckDuckGo's HTML endpoint (html.duckduckgo.com/html) via POST requests. Parses results with BeautifulSoup. Handles SafeSearch (kp param) and region (kl param) configuration.
WebContentFetcher — Fetches arbitrary URLs, strips non-content elements (script, style, nav, header, footer), and returns cleaned text truncated to 8000 chars. Parsed pages are kept in an in-memory TTLCache so pagination does not re-download.
RateLimiter — Sliding-window limiter (default). TokenBucketLimiter is the optional burst-then-smooth strategy. HostRateLimiter adds a per-host fetch cap. HTTP 429 honors Retry-After and retries once. Cache hits skip the fetch limiter.
TTLCache — TTL + LRU cache used by fetch_content. Disabled when TTL or max entries is 0.
LinkRegistry — In-memory LRU map behind ref://<id> tokens (issue #43). Search output replaces URLs longer than DDG_REF_URL_THRESHOLD with tokens; fetch_content resolves them before the SSRF guard; expand_link returns the original. Shared module-level instance links.

Read the full file on GitHub · 85 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago Changed · +7 lines · +413 tokens per session 89ddcbc63d3b
2mo ago First seen · 78 lines · 1,135 tokens per session scan A 7551529a85c5

Subscribe to this mod's changes

duckduckgo-mcp-server CLAUDE.md is an instructions file published in the GitHub repository nickclyde/duckduckgo-mcp-server (1,568 stars, last pushed 2mo ago), licensed MIT. It adds 1,548 tokens to every session, about $0.0062 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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duckduckgo-mcp-server: Instructions file for Claude Code