mcp-server-mattermost

unpin_message

Idempotent

Remove a pinned message from a Mattermost channel using its post ID. Unpinning a non-pinned message has no effect.

Instructions

Unpin a message from a channel.

Removes the message from the channel's pinned posts. Unpinning a non-pinned message has no effect.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`post_id`	Yes	26-character post/message identifier (e.g., 'o5w8h47pdfbzjc4d8w7dhnhren')

Output Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	Unique post identifier
`type`	Yes	Post type (empty for regular posts)
`edit_at`	Yes	Last edit timestamp
`message`	Yes	Post content (supports Markdown)
`root_id`	Yes	Root post ID if in thread
`user_id`	Yes	Author user identifier
`file_ids`	No	Attached file IDs
`hashtags`	Yes	Space-separated hashtags
`create_at`	Yes	Creation timestamp in milliseconds
`delete_at`	Yes	Deletion timestamp (0 if not deleted)
`is_pinned`	Yes	Whether post is pinned
`update_at`	Yes	Last update timestamp in milliseconds
`channel_id`	Yes	Channel where posted
`original_id`	Yes	Original post ID if edited
`pending_post_id`	Yes	Client-side pending ID

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.6.1Sep 10, 2026

changedOutput schema / required

Previous value: -[
-  "id",
-  "create_at",
-  "update_at",
-  "delete_at",
-  "edit_at",
-  "user_id",
-  "channel_id",
-  "root_id",
-  "original_id",
-  "message",
-  "type",
-  "hashtags",
-  "file_ids",
-  "pending_post_id",
-  "is_pinned"
-]New value: +[
+  "id",
+  "create_at",
+  "update_at",
+  "delete_at",
+  "edit_at",
+  "user_id",
+  "channel_id",
+  "root_id",
+  "original_id",
+  "message",
+  "type",
+  "hashtags",
+  "pending_post_id",
+  "is_pinned"
+]

First observedv0.5.1Jul 29, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description explicitly discloses the idempotent and non-destructive behavior by stating 'Unpinning a non-pinned message has no effect'. Annotations already provide idempotentHint=true and destructiveHint=false, but the concrete no-op behavior adds useful context beyond the structured hints.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two succinct sentences with no filler. The main action is front-loaded in the first sentence, and the second sentence adds only the relevant edge-case behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

This is a single-parameter, simple operation. The description, annotations, and input schema together cover the action, the idempotent edge case, and parameter format, so the tool is complete enough for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The sole parameter post_id is fully covered by the input schema (100% coverage) with type, format, and example. The tool description adds no additional semantic meaning to the parameter, so the baseline score of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'Unpin a message from a channel' and clarifies by saying it removes the message from the channel's pinned posts. This semantically distinguishes it from siblings like pin_message and delete_message without ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is provided on when to use this tool versus alternatives, nor are exclusions or prerequisites mentioned. The description only states the action itself, leaving the agent to infer that this should be used whenever a message needs unpinning.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.