teams-mcp-server

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mark_chat_unread

Set a Microsoft Teams chat as unread for the current user by specifying the last read timestamp, so messages after that time appear unread.

Instructions

Mark a chat as unread for the current user.

last_message_read_date_time: ISO 8601 timestamp of the last message that should be considered as read (e.g. "2026-03-26T10:00:00Z"). Messages after this timestamp will appear as unread.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "chat_id": "<chat_id>",
      "last_message_read_date_time": "<last_message_read_date_time>"
    },
    "name": "mark_chat_unread"
  }
}

Input Schema

Name	Required	Description	Default
`chat_id`	Yes
`last_message_read_date_time`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.5.0Oct 16, 2026

TDQS

B3.3/5.0

Behavior3/5

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

No annotations are supplied, so the description carries the full burden. It does disclose the meaningful behavioral rule for the timestamp (messages after it appear unread), which is real value, but says nothing about permissions, whether this is reversible, or side effects on notification state.

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

Conciseness4/5

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

The core action is front-loaded in one short sentence, followed by a focused explanation of the one non-obvious parameter. No filler, though the trailing 'Messages after this timestamp will appear as unread' slightly restates the preceding clause.

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

Completeness3/5

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

An output schema exists, so return values need not be described. However, for a mutation tool with no annotations, the description omits any mention of required permissions, reversibility, or effect on unread counts, leaving the agent short of a complete picture.

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

Parameters4/5

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

Schema description coverage is 0%, so the description must compensate, and it does for last_message_read_date_time by stating the ISO 8601 format, giving a concrete example, and explaining the semantic cutoff. chat_id is left unexplained, but its meaning is unambiguous from the tool name.

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

Purpose4/5

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

States a specific verb (mark) plus resource (chat) and scope (unread, for the current user), which is immediately actionable. It does not name the obvious sibling mark_chat_read or contrast the two, so sibling differentiation is left implicit.

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?

There is no when-to-use or when-not-to-use guidance, and the sibling list contains mark_chat_read, the natural alternative for the inverse operation. The agent must infer the read/unread relationship entirely on its own.

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