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fetch_external is Reacher’s general-purpose HTTP proxy. It forwards requests to external APIs, automatically injecting the right authentication token based on the target domain. Tokens stay on the server — Claude never sees them. This is the core insight behind Reacher’s design: Claude already knows REST APIs. It doesn’t need a dedicated tool for GitHub, Linear, or Notion. It needs a way to call those APIs with your credentials. fetch_external is that mechanism.
That’s three API integrations. One tool.

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Prerequisites

  • The target domain must be listed in PROXY_ALLOWED_DOMAINS (comma-separated)
  • For authenticated APIs, add the domain-to-token mapping in FETCH_EXTERNAL_TOKEN_MAP
When a request hits api.github.com, the tool looks up "api.github.com" in FETCH_EXTERNAL_TOKEN_MAP, finds "GITHUB_TOKEN", reads that env var, and injects Authorization: Bearer ghp_xxx automatically.

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Parameters

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string
required
The full URL to fetch. Must be a valid URL including scheme (e.g. https://api.github.com/user).
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string
HTTP method. Accepted values: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS. Defaults to GET.
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object
Request body for POST, PUT, and PATCH requests. Serialized as JSON. Content-Type: application/json is added automatically if not already present.
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object
Additional headers to include in the request. Merged with any injected auth headers. If you specify Authorization here it will be overridden by the injected token for the domain.

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Return value

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boolean
true if the HTTP response status was in the 2xx range (response.ok).
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number
HTTP status code returned by the upstream server.
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string
HTTP status text (e.g. "OK", "Not Found").
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object
Response headers as a key-value object.
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object | string
Parsed response body. JSON responses are returned as a parsed object. All other content types are returned as a string.
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string
The URL that was fetched.

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Security

When a request targets a domain not in PROXY_ALLOWED_DOMAINS, the tool returns immediately without making any network request:
This prevents the server from being used as a proxy to arbitrary destinations. Only explicitly allowed domains are reachable.

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Usage examples

For GitHub-specific searches (PRs by author, commits by date), use the dedicated github_search tool. It returns clean minimal output optimized for that use case.