---
title: "Answer a diagnostic question in one call"
method: GET
path: "/api/mcp/projects/{projectId}/investigate"
tags: ["Visibility"]
---

# Answer a diagnostic question in one call

`GET /api/mcp/projects/{projectId}/investigate`

## Request

- Base URL: `https://app.searchable.com`
- URL: `https://app.searchable.com/api/mcp/projects/{projectId}/investigate`
- Auth: HTTP bearer

Runs a whole multi-read chain server-side and in parallel, returning the measurements together instead of requiring five or six requests. `question=visibility_drop` (score trend + which engines moved vs the previous period + share-of-voice shift + weakest topics), `competitive_position` (standing with ranks and deltas + the topics where a rival leads), or `citation_gap` (citation trend + the domains AI answers cite + per-engine citation share). Returns measurements only, plus an `interpretation` list of what they cannot settle — it never names a cause. A signal whose upstream failed appears in `unavailable` with a reason rather than as a zero.

## Path parameters

- `projectId` string, uuid, required

## Query parameters

- `question` 'visibility_drop' | 'competitive_position' | 'citation_gap'
- `days` integer
- `from` string
- `to` string
- `platform` string
- `topicId` string, uuid
- `unbranded` 'true'
- `branded` 'true'
- `country` string
- `locationId` string

## Response `200`

The investigation's measured signals.

- InvestigateResponse: One diagnostic question answered by running its whole read chain server-side. Carries MEASUREMENTS plus an interpretation list of what they cannot settle — never a cause.
  - `question` 'visibility_drop' | 'competitive_position' | 'citation_gap', required
  - `project` object, required
    - `id` string, required
    - `name` string, required
    - `domain` string, nullable, required
  - `signals` object, required: Measured quantities for this question. Keys vary by question; a signal that could not be measured is absent here and listed in `unavailable` instead — never present as a zero.
  - `unavailable` object[], required: Signals whose upstream failed this run, with the reason. Missing data, not zero values.
    - `signal` string, required
    - `reason` string, required
  - `interpretation` string[], required: What the reader must still decide — present so the arithmetic above is not mistaken for an explanation.
  - `dateRange` object, required
    - `from` string, date-time, required
    - `to` string, date-time, required

## Other responses

- `400`: Error response. `code` is the machine-readable reason — see the [error reference](/api/errors) for the full catalog and remediation per code.
- `401`: Error response. `code` is the machine-readable reason — see the [error reference](/api/errors) for the full catalog and remediation per code.
- `403`: Error response. `code` is the machine-readable reason — see the [error reference](/api/errors) for the full catalog and remediation per code.
- `404`: Error response. `code` is the machine-readable reason — see the [error reference](/api/errors) for the full catalog and remediation per code.
- `429`: Rate limited. Usually the per-API-key REST limit (600 requests/minute); on Google-backed endpoints it can also relay an upstream Google rate limit. `Retry-After` (seconds) is present when the limit was applied by Searchable's own rate limiter; it may be absent when an upstream provider rate-limits.
- `504`: Error response. `code` is the machine-readable reason — see the [error reference](/api/errors) for the full catalog and remediation per code.

## Changes

- **2026-11-03** `28a5e2a65cd3`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/searchable/apis/searchable-rest-api/changes/api/mcp/projects/:projectId/investigate/get.md)

---

[API](https://skmtc.dev/searchable/apis/searchable-rest-api.md) - [All operations](https://skmtc.dev/searchable/apis/searchable-rest-api/llms.txt) - [OpenAPI document](https://skmtc.dev/searchable/apis/searchable-rest-api/revisions/a1cc70e46e73?raw)