Microsoft 365 MCP Server

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

Annotations already indicate this is a destructive write operation (destructiveHint: true, readOnlyHint: false). The description adds no behavioral context beyond the schema, such as whether this performs partial (PATCH) or full (PUT) updates, validation constraints, or the impact of updating read-only fields like 'id' or 'createdDateTime'.

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

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

The single sentence is efficiently structured and front-loaded, but is arguably too terse for a complex operation involving 4 parameters and deep nesting. No wasted words, though minimal content.

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

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

Given the tool's complexity (nested objects for recipients, attachments, flags, extended properties) and lack of output schema, the description is inadequate. It should clarify what 'eventMessage' means vis-à-vis regular messages and explain updatable versus read-only properties.

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

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

Schema description coverage is high at 75%, with detailed field descriptions in the nested 'body' object. The description provides no additional parameter guidance, but the baseline score of 3 is appropriate given the schema carries the semantic load.

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

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

The description uses a specific verb ('Update') and resource ('eventMessage object'), but creates confusion by referencing 'eventMessage' while the tool name is 'update-mail-message'. It fails to distinguish from sibling mail operations like forward-mail-message, reply-mail-message, or send-draft-message.

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

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

No guidance provided on when to use this tool versus alternatives like send-draft-message or reply-mail-message. No mention of prerequisites (e.g., requiring a message ID) or whether this applies to drafts, sent items, or received messages.

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