Similar By Target

biologyAvailable on FreeNo success wrapper

Returns drugs that share at least one protein target with the given drug, ranked by overlap, along with the shared targets and the resolved root drug and its variant forms. Use it to find drugs with a similar mechanism of action or to explore target-based drug relationships. Returns 404 when the drug key cannot be resolved.

When to use it

Find drugs that share targets with a given drug
Explore mechanism-of-action neighbors for a drug
List targets shared between a drug and its analogs

Getting started

Base URL

https://app.caelrith.com/api/v1/tools

Authentication

Include your API key in the x-api-key header.

Rate limit

Every call counts against your workspace’s daily quota for biology-associations. Exceeding it returns HTTP 429.

Plans and daily limits

Plan	Available	Calls / day
free	yes	10
pro	yes	200
custom (default)	yes	10,000

Plan defaults. A custom workspace may carry per-tenant overrides.

Parameters

Path parameters

Parameter	Type	Required	Description
key(path)	string	Yes

Query parameters

Parameter	Type	Required	Description
limit	integer	No	Range 1-100; default 20 (range 1-100; default 20) Range: 1 to 100

Example request

curl -H "x-api-key: YOUR_API_KEY" \
  "https://app.caelrith.com/api/v1/tools/biology/drugs/{key}/similar-by-target"

Response envelope

This endpoint returns an implicit 2xx response - there is no success flag in the body.

{
  "data": { /* payload */ },
  "meta": { /* pagination, totals */ }
}

// No "success" flag on this endpoint - any 2xx JSON is a success.

Catalog version mcp-2026-10-28 · generated from the live MCP catalog