Mattermost
Post, edit, search and thread messages in Mattermost channels, and manage channels and their members — on Mattermost Cloud and self-hosted servers alike.
About
Mattermost ships in the w6w first-party pack. It declares 13 actions, 3 health checks, and the host runs its code in a sandbox that never sees the credential.
- App id
io.w6w.mattermost- Version
- 0.1.2
- Author
- w6w
- Licence
- MIT
- Categories
- Communication · Productivity
Overview
Mattermost is a team messaging platform, self-hosted or on Mattermost Cloud, and this app posts and reads on it the way a person would: create, edit, delete and thread posts, search across them, and create channels and manage their membership.
Because a Mattermost install can be anyone’s own server, this app connects to whichever instance a workflow’s credentials point at rather than a single fixed host, and works the same way against a self-hosted deployment or Mattermost Cloud. Editing a post applies only the fields actually sent, so a workflow correcting one line of a message doesn’t blank out its attachments or other properties. Replying to a thread always resolves to the thread’s root, since Mattermost doesn’t support nested threads.
This app covers day-to-day messaging — posting, editing, searching, and managing channels and their members — rather than user or team administration, incoming/outgoing webhook configuration, or reactions and file attachments, which stay out of scope for this first pass.
Build with Mattermost
Three routes to the same 13 actions. The Workflow tab is generated from Mattermost's own manifest and carries its real ids, so it is copy-pasteable; the Code and CLI examples are the same call for any action on any app, so every app-specific value in them is a blank you fill in.
Open Direct Message Channel
channel-direct-create Open the direct-message channel between two users, creating it if it does not exist. Returns the same channel every time, so it is safe to call before each message.
Get Channel by Name
channel-get-by-name Resolve a team and channel name — the two segments of a Mattermost URL — to a channel, and so to the channel id every other action needs.
Add Channel Member
channel-member-add Add a user to a channel. They must already be on the channel's team.
List Channel Members
channel-members-list List a channel's memberships. Returns membership records — user ids and roles, not usernames.
List Channels for User
channels-for-user List the channels a user belongs to on a team. Defaults to this connection's own user.
Delete Post
post-delete Delete a post. Mattermost soft-deletes — the post stops being visible but survives until the server's retention policy removes it.
Update Post
post-update Edit a post's message, pin state or attachments. Only the fields you set are changed.
List Channel Posts
posts-for-channel List a channel's posts. Returns Mattermost's `{order, posts}` envelope — read `order` for the display order.
A workflow step names the app and the action, and the editor fills in the
connection when you pick one. This is the Step shape from the
workflow spec, carrying Mattermost's real ids.
{
"manifestVersion": "2",
"name": "mattermost-example",
"steps": [
{
"id": "channel-create",
"uses": {
"app": "io.w6w.mattermost",
"action": "channel-create",
"connection": "conn_YOUR_CONNECTION_ID"
},
"with": {
"teamId": "<teamId>",
"name": "<name>",
"displayName": "<displayName>"
}
}
]
}Here are some of the things you can do
-
Create Channel
performchannel-create -
Open Direct Message Channel
performchannel-direct-create -
Get Channel by Name
readchannel-get-by-name -
Add Channel Member
performchannel-member-add -
List Channel Members
searchchannel-members-list
+8 more actions available
Every app-specific value here is a blank you have to fill in. An
app action is reached through the connection that authenticates it, so the
address is a connection id, not the app id — and connections belong to your account,
so a public page cannot know yours. Create one for Mattermost, then fill in
the three blanks: conn_YOUR_CONNECTION_ID, the action key, and the
parameters that action declares. The call itself is real — the shape is transcribed
from the studio's own snippet builder, which prints the same kind of blanks — but
nothing in it is specific to Mattermost. The Workflow tab is where this app's
real ids are.
npm install @w6w/sdkyarn add @w6w/sdkpnpm add @w6w/sdkdeno add npm:@w6w/sdkimport { W6wClient, isActionRun } from "@w6w/sdk";
// Reads W6W_BASE_URL and W6W_TOKEN from the environment when omitted.
const client = new W6wClient();
const envelope = await client.run({
urn: "conn_YOUR_CONNECTION_ID",
action: "post-create",
payload: {
channelId: "<value>",
message: "<value>",
// rootId: "<value>",
// fileIds: "<value>",
// props: "<value>",
// priority: "<value>",
},
});
if (isActionRun(envelope)) console.log(envelope.value);npm install -g @w6w/cliw6w run conn_YOUR_CONNECTION_ID --action post-create --payload '{"channelId":"<value>","message":"<value>"}'Give an AI agent Mattermost — without giving it Mattermost's credentials. One MCP endpoint exposes every app, function and workflow the caller is entitled to, as tools it can discover and run. Access is granted per team while we onboard.
One tool call{
"name": "w6w_invoke",
"arguments": {
"ref": "app:io.w6w.mattermost#channel-create",
"input": {
"teamId": "<teamId>",
"name": "<name>",
"displayName": "<displayName>"
}
}
}
Every tool names its target with a single ref. The
app: form above doesn't name a connection at all — the
host resolves which of the caller's Mattermost connections to sign
with, and refuses rather than guesses when the answer is ambiguous.
What the agent gets
Credentials it can't read
The token is attached host-side, at the moment of the call. It is never a tool argument, never in the model's context, and never in a transcript — so a prompt injection has nothing to exfiltrate.
A tool surface scoped to the caller
Tools are derived per end user from what that person has actually connected and is entitled to — not one shared bot identity carrying the union of everyone's access.
A durable workflow in one call
Multi-step work runs on the workflow engine and returns a run handle the agent can poll — retries, branching and state survive the conversation that started them.
Health-aware discovery
Mattermost's declared health checks are on the surface too, so an agent can tell "the vendor is down" from "your credential expired" before it burns a retry on either.
The MCP surface is part of the hosted platform. Mattermost itself is MIT, and the runtime that executes it is source-available (FSL).
Health checks
Mattermost declares its own checks, so its health is a property of the app rather than something the host guesses at.
Mattermost Cloud status
Component status from status.mattermost.com (Atlassian Statuspage). Covers Mattermost's own hosting, sign-up and community — a self-hosted server is unaffected, which is why this check is informational and the per-connection `instance` check carries the weight.
Server reachable
Probes this connection's own Mattermost server at /api/v4/system/ping, which is unauthenticated by design — so the check runs unsigned and never sends the access token.
Rate-limit headroom
Reads X-Ratelimit-Remaining from this server. Mattermost only emits it when rate limiting is enabled in the System Console, which is off by default — hence informational.