Publer — REST proxy and MCP server¶

Status: MCP registration possible from this change; nothing has been published, scheduled or created on Publer by it. The readiness check below is dated 2026-10-07. Publer reaches this platform two ways: the REST proxy and calendar timer the Social Hub has used since the port, and, from this change, Publer's own MCP server, registered in the AI Engine. Both use the same key, PUBLER_API_KEY.

The two paths¶

	REST (Social Hub, calendar sync)	MCP (AI Engine)
Endpoint	`https://app.publer.com/api/v1`	`https://mcp.publer.com`
Caller	`publerProxy` (`functions/src/functions/integrations-http.js`) and `syncSocialCalendarScheduled` (`functions/src/lib/timers/publer-sync.js`)	`syncMcpTools` and `mcpProxy` (`functions/src/lib/ai/mcp.js`)
Key header	`Authorization: Bearer-API` followed by the key	`Authorization: Bearer` followed by the key
Workspace	`Publer-Workspace-Id` header from `PUBLER_WORKSPACE_ID`	Chosen through the tools (`select_publer_workspace`); one workspace locks itself. No header.
Policy	`assertSafePath` denylist; no path allowlist (estate review finding AP-B3)	`PUBLER_API_KEY` bound to `mcp.publer.com` only, no query string on that host, and a required tool allowlist (`allowedTools`, #995) enforced on every call (`functions/src/lib/ai/mcp-policy.js`)
Who can call	editor	Sync and calls to allowed tools: editor. Registering, changing the URL, key name or `allowedTools`, and switching the server on or off: super_admin

Two Publer behaviours that this repository measured and that its own documentation states the other way round:

401 means the workspace id is wrong, 403 means the key is (#358, measured 2026-09-09). The Keys tab has a light for each, and publerSettingForStatus decides which one a refusal turns red.
The MCP server takes a plain Bearer key. Publer's settings page shows Authorization: Bearer-API, but the server's own missing-key error says Use ?api_key=YOUR_KEY (or Authorization: Bearer YOUR_KEY). The AI Engine's resolver sends Bearer, and on 2026-10-07 a Sync through it reached the tool list, so no Publer-specific header code was needed.

Readiness check, 2026-10-07¶

Read-only throughout. Publer's MCP server was reached with a dummy key for initialize and tools/list, which are protocol metadata, and for one get_publer_user call, which is annotated read-only and was refused for the dummy key. No real key was used and nothing was written to Publer.

Item	State
`PUBLER_API_KEY` present server-side	Needs owner action: open the Keys tab and confirm the `Publer — API key` light is green. The setting is a Key Vault reference in `infra/functionapp.tf` (`PUBLER-API-KEY`). The light is set by the REST proxy and the calendar timer: a 403 turns it red, any success clears it, and nothing turns it green until one of them has called Publer. The MCP path does not report to this light.
`PUBLER_WORKSPACE_ID`	Ready for MCP, which does not use it. For the REST path it is the `Publer — workspace id` light on the same tab; a 401 turns it red.
REST proxy probe	Ready. The Publer card's Test button on Integrations → Services posts `{ path: '/accounts', method: 'GET' }` to `publerProxy`, which calls `GET https://app.publer.com/api/v1/accounts`. Good: `Connected — N social account(s).` AP-B3 (no path allowlist on `publerProxy`) is still open and is not changed here.
MCP server URL and auth	Ready. `https://mcp.publer.com`, Streamable HTTP: JSON-RPC over POST, replies framed as server-sent events, sessions by `mcp-session-id`, protocol `2024-11-05`, server `Publer Copilot MCP` 0.5.4. Key as `Authorization: Bearer` (accepted) or `Bearer-API` (documented). The `?api_key=` form Publer also accepts is refused here.
`PUBLER_API_KEY` allowed as an MCP key	Needs code: this change. Before it, `validateMcpApiKeyEnvVar` refused `PUBLER_API_KEY` at save and at call time. It is now on the list and bound to `mcp.publer.com` as its only host; every other host, `app.publer.com` included, is refused.
Write tools out of reach	Needs code: this change (#995). A server using `PUBLER_API_KEY` cannot be saved, and cannot be called, without a non-empty `allowedTools`. The API refuses a tool outside the list with 403 before any request leaves, for every role and for platform jobs alike. The seed's list is the 34 read and session tools.
Admin UI can register it at super_admin	Needs code: this change, then owner action. A disabled `Publer MCP` entry (`publer-mcp`) is now in the AI Engine seed. The seed writes it the first time a super_admin opens the MCP Servers tab. An editor-only account opening the AI Engine before that sees the seed error with a Retry button, because a new server needs super_admin.
Plan	Needs owner action: Publer offers MCP on Business and Enterprise (its help article also says Top Ambassadors on Enterprise, beta). A key on a plan without MCP is refused with `Invalid API key or not active for this account`.
Rate limit	Publer documents 100 requests per 2 minutes per user for its API. Nothing documents a separate MCP limit; assume MCP calls share it with the 5-minute calendar timer.

Publer MCP tools¶

tools/list on 2026-10-07 returned 47 tools. Read-only means the tool reads Publer and changes nothing there; "session" means it changes only which workspace, accounts, posts or media the MCP session has selected.

Read-only — safe to call: get_publer_user, list_publer_accounts, lookup_publer_accounts, list_publer_posts, lookup_publer_posts, list_publer_drafts, get_recent_posts, get_publer_job_status, get_post_insights, get_hashtag_insights, get_hashtag_performing_posts, get_best_times_to_post, list_analytics_charts, get_analytics_chart_data, get_members_analytics, analyze_recent_performance, list_competitors, get_competitors_analytics, list_publer_media, lookup_publer_media, list_media_options, generate_campaign_plan, search_publer_docs, read_publer_docs_page, search_publer_help, read_publer_help_article, load_publer_card_state.

Session only — no Publer data changes: list_publer_workspaces, select_publer_workspace, change_publer_workspace, select_publer_account, select_publer_posts, select_publer_media, save_publer_card_state.

Write — do not call from the Playground:

Tool	What it does
`submit_publer_posts`	Creates posts. `when` is `draft` (the default), `schedule`, `now` (publishes immediately), `auto`, `recycle` or `recur`.
`publish_publer_draft`	Publishes an existing draft immediately.
`update_publer_post`	Edits a scheduled, draft or published post in place.
`reschedule_publer_post`	Moves a scheduled post or draft.
`change_publer_post_state`	Promotes a draft to scheduled, or back.
`confirm_delete_publer_posts`	Deletes posts permanently.
`delete_publer_posts`	Annotated read-only, and deletes nothing itself, but it opens the delete preview that `confirm_delete_publer_posts` completes, so it is out.
`create_publer_post_from_file`, `create_publer_photo_draft`	Create drafts with media.
`create_publer_ideas`	Saves content ideas.
`upload_publer_media_from_url`, `upload_publer_chat_media`, `upload_publer_media`	Add files to the media library.

None of these 13 is callable here. The seeded server's allowedTools names the 34 read and session tools above and nothing else, and mcpProxy (and any platform job that calls an MCP tool) refuses every other tool with 403, naming the tool and the server, before any request reaches Publer, whatever the caller's role. A super_admin is refused too unless the list names the tool. The rules (#995, mcp-policy.js and admin-integrations/config-collections.js):

A server whose key is PUBLER_API_KEY must carry a non-empty allowedTools; saving one without it is refused, and a stored one without it refuses every call.
Only a super_admin can write allowedTools, and only a super_admin can switch a PUBLER_API_KEY server on or off. An editor's write naming either is refused with 403. A full PUT that omits the list keeps the stored one.
Sync stores the tool list Publer offers and never touches allowedTools, so a new Publer tool is not callable until a super_admin adds it.
Firecrawl, Replicate, the VPS token and keyless servers have no list and behave as before: any tool name. A list, once given, is enforced.
Every write records allowedTools before and after in the ai_config_updated audit row.

The card reads "34 of 47 tools allowed" once synced.

A narrower key. Publer keys carry scopes; Workspaces and Accounts are required, and Posts, Media and Analytics are optional. The Social Hub needs Posts, so PUBLER_API_KEY cannot be narrowed. A second key with Workspaces, Accounts and Analytics only would make the write tools fail at Publer. It would need its own setting, MCP_PUBLER_API_KEY, which needs a Terraform app setting and a Key Vault secret, and an MCP_* key is not bound to a host. Not done here.

Register and verify (owner)¶

Everything here is read-only. Sign in to the admin as the owner (super_admin).

Open https://hybridcloudworks.com/admin/integrations?tab=keys. The Publer — API key light should be green. If it is not, press Test on the Publer card at https://hybridcloudworks.com/admin/integrations?tab=services first; Connected — N social account(s). is a pass.
Open https://hybridcloudworks.com/admin/ai-engine?tab=mcp. The page writes the Publer MCP card: switched off, status untested, URL https://mcp.publer.com.
On that card press Sync Tools. Good: the toast says Tools synced with about 47 tools and the status turns connected. A sync succeeds even with a wrong key, because Publer lists its tools without checking the key, so this proves the connection and the policy, not the key.
Switch the card on (super_admin only for this server). The Playground lists only enabled servers with synced tools. The card should read 34 of 47 tools allowed.
Open https://hybridcloudworks.com/admin/ai-engine?tab=playground, choose MCP Tool, server Publer MCP, tool get_publer_user, arguments {}, and send. Good: your Publer name and plan. A refusal reading PERMISSION_DENIED with Invalid API key or not active for this account means the key is wrong or the plan has no MCP; the REST light on Keys stays as it was, because the MCP path does not report to it.
Optionally, tool lookup_publer_accounts, arguments {}. Good: the connected social accounts. If it answers selection_required with workspace names, the key read the workspaces and that is a pass too; choosing one is a session change only, and not needed for this check.
Switch the card off again until there is a use for it.

If the URL field ever shows ?api_key=, it was not saved: the save is refused with must not carry a query string. That refusal is the policy working. Publer's "Server URL" is not the URL to paste; https://mcp.publer.com is.

Sources¶

Publer, How to set up and use Publer's MCP server (updated 2026-09-28): setup, scopes, plan, the Server URL and Authorization header screenshots.
Publer, API documentation: base URL, the Bearer-API scheme, Publer-Workspace-Id, 100 requests per 2 minutes.
The server itself, 2026-10-07: initialize (server name, version, instructions, the missing-key error) and tools/list (names and readOnlyHint / destructiveHint annotations).