Agent Search MCP: Free Web Search for AI Agents

A lightweight, free-first MCP web search router with compact multi-source evidence.

Agent Search MCP is an open-source, self-hosted MCP server and CLI. It starts without an API key, searches English and Chinese sources, keeps optional paid providers behind an explicit policy, and caps provider calls, search time, result count, and evidence size.

中文文档 · Benchmarks · Architecture · CHANGELOG

Install

npx -y agent-search-mcp

Requires Node.js >= 18.17. The default runtime does not require a browser, database, Python, or a search API account.

Connect an MCP client

Use this stdio configuration in MCP clients that accept mcpServers JSON, including Claude Desktop, Cursor, VS Code, and Windsurf:

{
  "mcpServers": {
    "agent-search": {
      "command": "npx",
      "args": ["-y", "agent-search-mcp"]
    }
  }
}

Claude Code and Codex can register the same npx -y agent-search-mcp stdio command through their MCP settings.

After a global install, check the local runtime without making a search request:

npm install -g agent-search-mcp
fasm doctor

Why Agent Search MCP

The default free_first policy never spends a configured API credential. free_only blocks paid providers. quality_escalation can call one configured paid provider after free evidence misses the quality gate, while paid_first tries that provider before the free fallback.

Request budgets cap adapter attempts, elapsed time, and admitted results. The evidence budget caps query-relevant passages across the complete response. Compact mode keeps full detail for the first results and reduces later entries to source-preserving references.

Measured token reduction

The checked-in bilingual fixture measures formatting with a locked tokenizer:

This fixture verifies output formatting and evidence-packet behavior. It does not measure live engine availability or search quality. See the benchmark method and limitations.

How the search router works

flowchart LR
    A["AI agent"] --> M["MCP search tools"]
    M --> P["Provider and request policy"]
    P --> F["Zero-key sources"]
    P --> O["Optional paid provider"]
    F --> E["Deduplicate, rank, and preserve failures"]
    O --> E
    E --> B["Evidence and token budget"]
    B --> R["Compact multi-source result"]

The router evaluates each search batch against separate result, relevance, confidence, and provider-family gates. It stops after the evidence passes those gates and exposes the decision in meta.execution. Provider failures stay visible in partialFailures, so an empty result cannot hide an upstream error.

The source-level product comparison explains where Agent Search MCP differs from Tavily, Exa, Brave Search, Firecrawl, and MCP Web Hound. It compares routing, evidence, local operation, paid-provider boundaries, and Chinese search without volatile pricing or popularity claims.

Engines

The runtime registers 16 adapters: 9 zero-key adapters and 7 optional API adapters.

Tools

Capability controls

Wiby is a genuine zero-key source backed by its official JSON API and is used late in the free waterfall as an independent small-Web supplement. Optional providers require user credentials; any signup credit or trial quota is provider-controlled and is not treated as permanent free access.

All tools are read-only and idempotent. Search cancellation reaches rate-limit waits, retries, provider requests, and optional enrichment. Enrichment can improve a snippet but cannot increase source confidence or independent source count.

free_search_advanced.time_range remains in the compatibility schema. The server returns UNSUPPORTED_FILTER before searching because the general web providers do not share one enforceable recency contract.

Configuration

The generated capability table above lists the default request budgets. These settings cover the common deployment choices:

Adding an API key does not authorize paid traffic. The routing policy controls provider use. The default exact-result cache stays in memory; setting SEARCH_CACHE_DIRECTORY opts into local persistence. Semantic processing is the only optional feature that uses Python and Model2Vec.

HTTP deployment

HTTP mode requires HTTP_AUTH_TOKEN unless you set HTTP_ALLOW_UNAUTHENTICATED=true. Browser requests with an Origin header must match ALLOWED_ORIGINS. See the HTTP deployment guide for TLS termination, token rotation, and reverse-proxy examples.

CLI

The package includes the fasm CLI:

fasm search "TypeScript MCP server"
fasm search "query" --count 5 --engines bing,baidu,youcom --json
fasm extract "https://example.com"
fasm extract "https://example.com" --json
fasm doctor
fasm doctor --json
HTTP_AUTH_TOKEN=change-me MODE=http npx agent-search-mcp

fasm doctor reads local configuration without network probes and never prints credential or proxy values.

Documentation and evidence

Companion: Slim Guard

Agent Search controls retrieval work and compresses search evidence. mcp-slim-guard sits between an agent and MCP servers to handle tool-schema compression and security policy.

npm install -g mcp-slim-guard

Development

git clone https://github.com/lennney/agent-search-mcp.git
cd agent-search-mcp
npm install
npm run build
npm test
npm run dev        # stdio mode
npm run dev:http   # HTTP mode (port 3000)

The stable package supports Node.js 18, 20, and 22. The isolated MCP 2026 experiment requires Node.js 20 or newer.

License

Apache 2.0

Based on open-websearch by Aas-ee.

If Agent Search MCP helps your agent, star the repository so other developers can find the project.