Universal Web Retrieval MCP

A universal MCP server providing resilient web search and content retrieval through a configurable provider chain — AnySearch, Tavily, DDGS, Tencent Yuanbao Search, Bocha, DeepSeek, Kimi, Zhipu BigModel, Brave Search and Jina Reader — with automatic failover.

Quick Start

No API key is required. With no keys configured the server uses the keyless mode of AnySearch/Tavily and falls back to keyless DDGS.

uvx (zero config, recommended):

{"mcpServers": {"universal-web-retrieval": {"command": "uvx", "args": ["uwr"]}}}

npx (same server, no Python toolchain needed — the launcher fetches a runner):

{"mcpServers": {"universal-web-retrieval": {"command": "npx", "args": ["-y", "@withgardener/uwr"]}}}

pip:

pip install uwr
uwr        # stdio MCP server

API keys are optional: add TAVILY_API_KEY, ANYSEARCH_API_KEY (or any of the others) to the env block when you have them. See Configuration.

Related MCP server: Search Toolkit

Overview

Give any MCP-capable agent reliable web access through a single server. Universal Web Retrieval routes each request through an ordered provider chain, picks keyed or keyless authentication automatically based on which API keys are present, and moves to the next provider on rate limits, outages, or upstream errors.

The active chains are selected in this order:

1. providers argument passed for the call.

2. Environment configured chain (UWR_SEARCH_CHAIN or UWR_FETCH_CHAIN).

3. Built-in default (anysearch,tavily,ddgs).

providers=None selects the configured chain. An explicitly empty list, providers=[], is invalid input; it never means "use defaults". Jina Reader works keyless and is deliberately absent from both defaults. New providers are opt-in, preserving the default behavior from 0.1.x.

Agent (any MCP client)
│
├── web_search ──▶ chain from UWR_SEARCH_CHAIN   (default: AnySearch → Tavily → DDGS)
└── web_fetch  ──▶ chain from UWR_FETCH_CHAIN    (default: AnySearch → Tavily → DDGS.extract)

Features

• Three standard tools — web_search, web_fetch, and list_providers, clean JSON in/out.

• Configurable chains — UWR_SEARCH_CHAIN / UWR_FETCH_CHAIN set the order; UWR_DISABLED_PROVIDERS switches providers off without editing the chains.

• Per-call override — web_search(..., providers=["bocha"]) or ["yuanbao","tavily"] runs just that order for one call.

• Automatic provider failover — one provider failing never fails the tool.

• Opt-in fan-out — mode="fanout" queries up to N providers concurrently and rank-fuses the answers (RRF) instead of taking the first one. See Search modes.

• Auto keyed/keyless — key configured → official keyed API; key absent → official keyless access (where the provider offers one). Keyed-only providers (Yuanbao, Bocha, DeepSeek, Kimi, Zhipu, Brave) without a key are skipped, never attempted, so a missing key cannot 401 the chain.

• Strict official APIs — every provider is called through its official documented endpoint and auth mechanism. No scraping hacks, no undocumented endpoints.

• Error classification — rate limits / outages fall over; invalid credentials fail loudly (ERROR log) and move to the next provider; malformed input never triggers fallback.

• Bounded latency — per-provider timeouts are capped to the remaining chain budget; the router does not start a provider call once less than 100 ms remain.

• Observable — every response carries provider, mode, latency_ms and an attempts trail.

• Zero agent coupling — standard MCP stdio; works with Hermes, Claude Code, OpenCode, or any MCP client.

Architecture

src/universal_web_retrieval/
├── server.py            # MCP tool surface (web_search / web_fetch / list_providers)
├── config.py            # env-driven settings, call-time key + chain reads
├── errors.py            # ProviderError classification, result models, Provider ABC
├── fanout.py            # URL dedupe + Reciprocal Rank Fusion merge (fan-out mode)
└── providers/
    ├── registry.py      # name -> provider instance; capability lookup
    ├── router.py        # chain resolution (env / override / default) + failover + fan-out
    ├── anysearch.py     # AnySearch (keyed Bearer / keyless no-auth-header)
    ├── tavily.py        # Tavily (keyed Bearer / keyless X-Tavily-Access-Mode)
    ├── ddgs.py          # DDGS (official package; text + extract)
    ├── yuanbao.py       # Tencent Yuanbao Search (MCP over Streamable HTTP, Bearer)
    ├── bocha.py         # Bocha Web Search API (REST, Bearer)
    ├── deepseek.py      # DeepSeek Search + Fetch API (REST, Bearer)
    ├── kimi.py          # Kimi/Moonshot search + search_pro + fetch (REST, Bearer)
    ├── zhipu.py         # Zhipu BigModel web_search (REST, Bearer)
    ├── brave.py         # Brave Search API (REST, X-Subscription-Token)
    └── jina.py          # Jina Reader r.jina.ai (keyless or Bearer, fetch only)

Installation

pip install uwr                    # from PyPI
uvx uwr                            # or run without installing
npx -y @withgardener/uwr           # or through the npm launcher

uwr --version                      # uwr 0.3.0
uwr                                # run the stdio MCP server

ddgs is a runtime dependency (the fixed final fallback of the default chains), not an optional extra. Dependencies are pinned to compatible ranges (mcp>=2,<3, httpx>=0.27,<1, ddgs>=9.16,<10) so a major-version breaking change never ships to a running server via a routine pip update.

From source (development)

git clone https://github.com/withgardener/universal-web-retrieval-mcp.git
cd universal-web-retrieval-mcp
pip install -e .

uwr                                # or: PYTHONPATH=src python -m universal_web_retrieval

Configuration

Chains

Resolution rules:

1. A per-call providers argument wins (it only affects that call).

2. Otherwise UWR_SEARCH_CHAIN / UWR_FETCH_CHAIN.

3. Otherwise the built-in defaults above — 0.2.0 is behaviour-compatible with 0.1.x out of the box.

Unknown names, providers lacking the capability, and disabled providers are dropped with one warning per distinct chain (not once per request). A chain that resolves to nothing falls back to the defaults. An explicitly empty/invalid per-call override is an input error instead — providers=["bocha"] never silently becomes the whole default chain.

Keys and tuning

Every key is read at call time, so a restart of the MCP server process is enough for new values to take effect (for Hermes: the mcp_servers env is frozen at gateway start — restart the gateway or kill the child process).

Tools

web_search(query, limit=5, providers=None, mode=None)

{
  "success": true,
  "provider": "anysearch",
  "mode": "keyless",
  "latency_ms": 1555,
  "attempts": [{"provider": "anysearch", "outcome": "ok"}],
  "results": [{"title": "...", "url": "...", "snippet": "..."}]
}

When a provider exposes publication date / site (Yuanbao, Bocha, DeepSeek, Kimi, Zhipu, Brave), the result rows also carry published, site and (where scored) score. provider / mode / latency_ms / attempts are diagnostic metadata — consumers only need results.

mode selects the search mode for this call ("failover" or "fanout", see Search modes); omit it to use UWR_SEARCH_MODE. In fan-out mode provider is "fanout", mode is the shared auth mode of the answering providers (or "mixed"), attempts entries for successful providers also carry results and latency_ms, and every result row carries sources (provider names in chain order):

{
  "success": true, "provider": "fanout", "mode": "keyed", "latency_ms": 812,
  "attempts": [
    {"provider": "bocha", "outcome": "ok", "results": 5, "latency_ms": 640},
    {"provider": "tavily", "outcome": "ok", "results": 5, "latency_ms": 790},
    {"provider": "ddgs", "outcome": "skipped:grace"}
  ],
  "results": [{"title": "...", "url": "...", "snippet": "...", "sources": ["bocha", "tavily"]}]
}

attempts is the per-provider outcome trail in chain order:

Success schema (search): {"success": true, "provider": ..., "mode": ..., "latency_ms": ..., "attempts": [...], "results": [...]}. Provider error schema: {"success": false, "error": "...", "attempts": [...]}. Invalid-input schema: {"success": false, "error": "invalid input: ..."} (no attempts). Fetch returns one object per URL with url, content, content_type, title, provider, mode, latency_ms, and attempts; failed URLs carry error and attempts instead of success metadata.

Sample failure of a mixed chain (UWR_SEARCH_CHAIN=yuanbao,bocha,ddgs with no Yuanbao/Bocha keys):

{
  "success": false,
  "error": "all providers failed: yuanbao: skipped (not_configured) | bocha: skipped (not_configured) | ddgs(keyless): HTTP 429 rate limited: ...",
  "attempts": [
    {"provider": "yuanbao", "outcome": "skipped:not_configured"},
    {"provider": "bocha", "outcome": "skipped:not_configured"},
    {"provider": "ddgs", "outcome": "error:HTTP 429 rate limited: ..."}
  ]
}

Per-call override:

{"query": "腾讯 财报", "providers": ["bocha"]}          // Bocha only
{"query": "腾讯 财报", "providers": ["yuanbao", "tavily"]}  // try Yuanbao first

An override that contains no usable provider (including providers=[]) is an input error. providers=None means use the configured chain; an empty explicit list never falls back to the defaults.

web_fetch(url | urls, providers=None)

Accepts a single url string or a urls array (max 5) and an optional providers override. Returns a JSON array:

[{
  "url": "https://example.com",
  "content": "# Example Domain\n\n...",
  "content_type": "text_markdown",
  "title": "Example Domain",
  "provider": "anysearch",
  "mode": "keyless",
  "latency_ms": 191,
  "attempts": [{"provider": "anysearch", "outcome": "ok"}]
}]

Failed URLs carry an error field instead of content. Content is Markdown/clean text — never raw HTML. JS-rendered, login-walled, or CAPTCHA-protected pages are not guaranteed (plain HTTP retrieval only; no browser automation).

list_providers()

Returns every provider this build knows, with capability, configuration status, enabled flag and its 1-based position in each active chain, plus the active search_mode and the fan-out settings (fanout.n, fanout.grace_s). Key values are never returned.

{
  "chains": {"search": ["anysearch", "tavily", "ddgs"], "fetch": ["anysearch", "tavily", "ddgs"]},
  "defaults": {"search": ["anysearch", "tavily", "ddgs"], "fetch": ["anysearch", "tavily", "ddgs"]},
  "search_mode": "failover",
  "fanout": {"n": 3, "grace_s": 5.0},
  "disabled": [],
  "providers": [
    {"name": "bocha", "kind": "search", "capabilities": ["search"], "keyed_only": true,
     "configured": false, "auth_mode": null, "enabled": true, "position": {"search": null}},
    {"name": "anysearch", "kind": "search", "capabilities": ["fetch", "search"], "keyed_only": false,
     "configured": true, "auth_mode": "keyed", "enabled": true,
     "position": {"search": 1, "fetch": 1}}
  ]
}

Network scope & SSRF note

web_fetch retrieves any URL the host environment can reach — this deliberately includes private-network and localhost targets, which is a legitimate capability for a local agent tool. Redirects may land on private or link-local destinations. When deploying against untrusted agent input, apply network-level isolation (container/netns/firewall) as appropriate for your threat model. A future WEB_RETRIEVAL_BLOCK_PRIVATE=1 opt-in may add in-process filtering; it is intentionally not implemented yet.

Batch behavior: urls is capped at 5 per call (larger batches are rejected with an explicit error, not silently truncated), duplicates are de-duplicated preserving first-seen order, and the whole batch shares one deadline — URLs whose turn arrives after the deadline return a timeout error without any network attempt. Error text containing URLs has credential-looking query parameters (token=, api_key=, ...) redacted.

Routing & fallback

A link is skipped when: rate-limited (429), timed out, upstream 5xx, or any provider error. Invalid credentials fail loudly (ERROR log AUTH FAILURE on <provider>) and the chain moves to the next provider — a wrong key is never silently retried as keyless on the same provider. Malformed input (empty query, bad URL scheme) returns an immediate input error with no fallback.

Example chains (not defaults). Defaults stay minimal so existing deployments are unchanged. If you hold the keys, this is a sensible China-friendly ordering — deepseek/kimi give independent indexes and correct published dates, and ddgs stays last as the keyless floor:

UWR_SEARCH_CHAIN: anysearch,tavily,deepseek,kimi,yuanbao,ddgs
UWR_FETCH_CHAIN: anysearch,tavily,deepseek,kimi,ddgs

Every one of those links is either free or priced per call (see the table below), and each one falls through on error, so a longer chain costs nothing when earlier links succeed. Two rules worth keeping:

• Keep ddgs last — keyless, no quota, the floor of the chain.

• Never put jina in a default chain — it works without a key, so a stale/keyless deployment would start sending every fetch through it. Add it explicitly when you want its Markdown quality, e.g. UWR_FETCH_CHAIN: anysearch,tavily,jina,ddgs.

Search modes

web_search has two modes. The default is unchanged from every earlier release.

The trade-off: fan-out spends N× provider quota per search, and its latency is bounded by the grace window (at most UWR_FANOUT_GRACE seconds more than the fastest provider) and by the shared chain deadline (WEB_RETRIEVAL_TIMEOUT) — never by the slowest provider. In exchange it buys agreement: a page several providers return outranks a page only one of them found, which is what you want when a wrong first hit is expensive.

Latency and quota

Measured on the default chain (anysearch,tavily,ddgs) with N=3 and the default 5 s grace:

In the slow case the first two providers answered at about 2.1 s and ddgs was still running when the grace window closed: the response came back at about 7 s with ddgs recorded as skipped:grace. All three calls were made either way, so every fan-out spends N× provider quota — including the ones whose answers are thrown away. An abandoned provider keeps running in its daemon thread and may still complete (and be billed) in the background; the grace window decides what you wait for, not what you pay for.

Selecting a mode:

• UWR_SEARCH_MODE=fanout (or failover) sets the default for every call. An unknown value logs one warning and falls back to failover.

• web_search(..., mode="fanout") overrides the default for one call. An unknown per-call value is an input error — it never silently switches modes.

• In fan-out mode providers still defines the candidate order; its first N eligible entries are queried. Keyed-only providers without a key are recorded as skipped:not_configured and do not consume a slot.

• UWR_SEARCH_FANOUT (default 3, minimum 1, clamped to the chain length) sets N.

Merging (fanout.py):

1. URLs are normalised for dedupe into a scheme-less key, //host[:port]/path?query, so http:// and https:// for one page collapse — as does a default port (:80 for http, :443 for https). The host is IDNA-normalised with any leading www. stripped (non-default ports and IPv6 literals preserved), the fragment and tracking parameters (utm_*, gclid, fbclid, mc_cid, mc_eid, ref, ref_src, spm) dropped, remaining parameters sorted, and a trailing / removed (except for the root path). The output keeps the best-ranked occurrence's original URL, not the key.

2. Reciprocal Rank Fusion: score = Σ 1/(60 + rank) over every provider that returned the URL, with a 1-based rank inside that provider's list. Ties break on number of sources, then best single rank, then chain order.

3. Per row: title and URL from the best-ranked occurrence, the longest non-empty snippet, and published / site from the first non-empty value in chain order. Every row gains sources — the provider names, in chain order.

Fan-out responses set provider: "fanout" and mode to the shared auth mode of the answering providers, or "mixed" when they differ. attempts carries one entry per queried provider: ok (plus results and latency_ms), error:<msg>, skipped:not_configured, skipped:fanout (beyond the N-provider cutoff), skipped:grace (a late successful answer is discarded; a late error stays visible) or skipped:deadline. Success requires at least one provider to answer OK, not at least one hit: if every answering provider returns an empty list, the response is a success with results: [] and ok / results: 0 entries in attempts — the same thing failover returns for that query. Only when no provider answers OK at all is it the same all providers failed: ... error with the trail attached, and one provider's fallback_eligible=False error does not abort the others.

{"query": "rust async runtime", "mode": "fanout",
 "providers": ["bocha", "tavily", "ddgs"]}

web_fetch is always failover: there is nothing to merge for a single URL.

Concurrency: providers are synchronous HTTP clients, so fan-out starts one daemon thread per selected provider — plain threading.Thread plus a queue.Queue of (provider, outcome) records, no new dependency and no private interpreter internals. Each worker gets its own timeout budget and shares no mutable per-call state. Yuanbao is the only provider holding per-instance state (MCP session id and JSON-RPC counter); both are guarded by an RLock, and a concurrent handshake race costs one extra session, not correctness. A straggler that outlives the grace window keeps running in its daemon thread; the collector never joins it, it cannot delay interpreter exit, and the result it eventually posts is dropped.

Provider behavior

The built-in chain remains anysearch,tavily,ddgs for search and fetch; all newly added providers are opt-in unless explicitly listed in UWR_SEARCH_CHAIN, UWR_FETCH_CHAIN, or a per-call providers override. Jina is keyless but deliberately absent from defaults.

See docs/providers.md for each provider's official endpoint, auth mechanism, keyless behavior, pricing notes and last-verified date.

Official sources for every row are listed in docs/providers.md. Prices are catalogue list prices as published on 2026-10-20 and may change; the provider's own pricing page is authoritative.

Examples

All provider keys below are placeholders or environment-variable references; never put live credentials in client configuration files.

Generic MCP client (stdio)

{
  "mcpServers": {
    "universal-web-retrieval": {
      "command": "uvx",
      "args": ["uwr"],
      "env": {
        "ANYSEARCH_API_KEY": "${ANYSEARCH_API_KEY}",
        "TAVILY_API_KEY": "${TAVILY_API_KEY}",
        "UWR_SEARCH_CHAIN": "anysearch,tavily,bocha,ddgs"
      }
    }
  }
}

Swap "command": "uvx", "args": ["uwr"] for "command": "npx", "args": ["-y", "@withgardener/uwr"] where npm is the only package manager available, or for "command": "python", "args": ["-m", "universal_web_retrieval"] when running the from-source checkout with PYTHONPATH set.

Hermes Agent

In ~/.hermes/config.yaml:

mcp_servers:
  universal-web-retrieval:
    command: /root/.local/bin/uvx
    args: ["uwr"]
    transport: stdio
    enabled: true
    env:
      ANYSEARCH_API_KEY: ${ANYSEARCH_API_KEY}
      TAVILY_API_KEY: ${TAVILY_API_KEY}
      # optional, only if the corresponding key is provided:
      # YUANBAO_API_KEY: ${YUANBAO_API_KEY}
      # BOCHA_API_KEY: ${BOCHA_API_KEY}
      # DEEPSEEK_API_KEY: ${DEEPSEEK_API_KEY}
      # MOONSHOT_API_KEY: ${MOONSHOT_API_KEY}
      # ZHIPU_API_KEY: ${ZHIPU_API_KEY}
      # BRAVE_API_KEY: ${BRAVE_API_KEY}
      # JINA_API_KEY: ${JINA_API_KEY}
      # UWR_SEARCH_CHAIN: anysearch,tavily,deepseek,kimi,yuanbao,ddgs
      # UWR_FETCH_CHAIN: anysearch,tavily,deepseek,kimi,ddgs

Claude Code

claude mcp add universal-web-retrieval \
  --env TAVILY_API_KEY="${TAVILY_API_KEY}" \
  -- uvx uwr

Cursor

Add a project .cursor/mcp.json or user MCP configuration with environment variables supplied by the launching process:

{
  "mcpServers": {
    "universal-web-retrieval": {
      "command": "uvx",
      "args": ["uwr"],
      "env": {
        "ANYSEARCH_API_KEY": "${ANYSEARCH_API_KEY}",
        "TAVILY_API_KEY": "${TAVILY_API_KEY}"
      }
    }
  }
}

For Cursor releases using its ${env:NAME} interpolation syntax, use "${env:ANYSEARCH_API_KEY}" and "${env:TAVILY_API_KEY}". Verify environment substitution on your Cursor version; do not replace these references with literal credentials.

Development

pip install pytest
pytest tests/unit -v            # chain/override/attempts/provider unit tests (no network)

# Live provider smoke tests (hit real APIs; opt-in):
RUN_LIVE_TESTS=1 pytest tests/integration -v

Unit tests clear provider keys and UWR_* variables per test, so the suite is hermetic — it passes with or without keys exported in your shell. New providers are covered with mocked HTTP only (no keys needed, no live calls).

License

MIT