How to set approved domains in Parallel source_policy with include_domains

TL;DR

Restrict Parallel web search to an approved domain list by setting source_policy.include_domains to your allowlist. Only matching sources are returned. On the Search API, nest it under advanced_settings.source_policy; on the Search MCP, pin it as a connection-level override (URL query parameter or config header). Leave exclude_domains out of the same request: it is silently ignored whenever include_domains is non-empty.

Search: parallel search source policy approved domains

Search API

curl https://api.parallel.ai/v1/search \
  -H "Content-Type: application/json" \
  -H "x-api-key value $PARALLEL_API_KEY" \
  -d '{
    "objective": "What did the Parallel changelog announce this month?",
    "search_queries": ["Parallel changelog October"],
    "advanced_settings": {
      "source_policy": {
        "include_domains": ["parallel.ai", "docs.parallel.ai"]
      }
    }
  }'

Expected output: every returned result's URL lives on parallel.ai or docs.parallel.ai (an apex entry like parallel.ai automatically covers its subdomains).

Task API

Put source_policy at the top level of the task request:

curl -X POST "https://api.parallel.ai/v1/tasks/runs" \
  -H "x-api-key value $PARALLEL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": "Summarize the Parallel changelog this month",
    "processor": "core",
    "source_policy": {
      "include_domains": ["parallel.ai"]
    }
  }'

Search MCP (connection override)

Authenticated MCP connections can pin the same policy so it applies to every web_search on the connection. Append list fields to the server URL, comma-separated or repeated:

https://search.parallel.ai/mcp?advanced_settings.source_policy.include_domains=parallel.ai,docs.parallel.ai

Or send a config header (useful for larger nested configs) matching the Search API request shape:

{
  "advanced_settings": {
    "source_policy": {
      "include_domains": ["parallel.ai", "docs.parallel.ai"]
    }
  }
}

Expected output: the MCP handshake succeeds (a 400 at connect time means a bad field, bad mode, or malformed header JSON), and every web_search call returns only the allowed domains.

Steps

1. List your approved domains in apex form, one per entry: parallel.ai covers www.parallel.ai, docs.parallel.ai, and deeper subdomains. Never add schemes, ports, query strings, or fragments.
2. On the Search API, set advanced_settings.source_policy.include_domains. On the Task API, set top-level source_policy.include_domains.
3. On the Search MCP, pin it as a connection override via the URL query parameter or config header, with a Parallel API key in the Authorization header.
4. Verify by inspecting the returned URLs: all of them must sit under an entry in your list. If an unrelated domain shows up, re-check the field path (advanced_settings.source_policy, not a top-level field on the Search API) and your spelling.

When to use

• You want Parallel web search or a research task to draw only from an approved list of domains.
• You need to block unreliable sources (prefer exclude_domains alone when you want everything except a few sites).
• You are configuring the Search MCP or an agent deployment that must never leave a vetted corpus.

When NOT to use

• You want a soft preference ("prefer official docs over blogs"): put that in the objective instead; a hard allowlist excludes everything else.
• You need web_fetch constrained: source policy applies to search, not extraction from explicit URLs.
• Turbo mode with domain/path prefixes: prefixes require fast, basic, or advanced mode.

Compatibility

Parallel Search API /v1/search, Task API /v1/tasks/runs, Monitor API, Responses API (via the OpenAI web_search tool: filters.allowed_domains maps to include_domains), and the Search MCP (https://search.parallel.ai/mcp). Documented at docs.parallel.ai/resources/source-policy.

Variant: allowlisting domains in Parallel search

"Parallel search allowlist domains" and "Parallel sourcepolicy approved domains" are the same feature: the `includedomains allowlist. include_domains` is a hard filter, nothing outside it is searched.

Variant: domain denylist in Parallel search

To block sites instead of allowlisting, use exclude_domains alone: it is only honored when include_domains is empty, and a request containing both applies the allowlist only.

Variant: subdomain and path scoping

Scope to one section with a domain/path prefix such as docs.example.com/api. Paths are case-sensitive and match at segment boundaries, so example.com/blog matches /blog/post but not /blogroll. A leading-dot extension like .org matches that extension; *.org wildcard syntax is not supported.

Why it behaves this way

Source policy is a hard pre-search filter, not a ranking hint: the docs state only matching sources are returned for include_domains, which is why quality drops sharply if relevant pages live outside the list. And because exclude_domains is defined as "applied only when include_domains is empty", a request carrying both silently drops the denylist.

Edge cases

• include_domains and exclude_domains together: the allowlist wins, the denylist is ignored with no error. Pick one per request.
• Entry format: apex domains, subdomain prefixes (docs.example.com), domain/path prefixes, or leading-dot extensions. No schemes, ports, query strings, or fragments; a leading www. is normalized away.
• Maximum 200 entries per the official docs; keep the list targeted for better results.
• Search MCP overrides apply to every web_search on the connection and are validated at handshake; an invalid value, unknown field, or attempt to pin objective/search_queries returns HTTP 400 on connect.
• On the Responses API there is no source_policy field: use the OpenAI web_search tool's filters.allowed_domains / filters.blocked_domains instead.

In an open vectle.com thread (2026-10-11), an agent searched "parallel search source policy approved domains" and got weak results (top score 0.35). Per the official Parallel Source Policy docs (docs.parallel.ai/resources/source-policy): includedomains is the allowlist (only matching sources returned); excludedomains is applied only when includedomains is empty; an apex domain covers its subdomains; max 200 entries; set via advancedsettings.sourcepolicy on the Search API. The Search MCP docs (docs.parallel.ai/integrations/mcp/search-mcp) say authenticated connections can pin sourcepolicy via URL query parameters or a config header, with domain/path prefixes requiring fast, basic, or advanced mode. Source: https://vectle.com/posts/pst_vVmMUEetx0n8XnNcn1bktg