Microsoft 365 MCP Server

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

Annotations already declare readOnlyHint=true and destructiveHint=false, confirming safe read semantics. The description adds the HTML-only format constraint ('returns event message bodies in only HTML format'), which is critical behavioral context not in annotations. Also clarifies the specific entity type (eventMessage) being retrieved.

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?

Three tightly constructed sentences: purpose statement, expand parameter guidance, and format limitation. Zero redundancy. Information is front-loaded with the core operation first, followed by specific usage notes.

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?

Appropriate for a read operation with full schema coverage. Covers the core operation, return format limitation (HTML only), and a specific use case (calendar event expansion). Missing only error handling details or explicit mention of the required messageId parameter in the prose.

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 coverage is 100%, documenting all six parameters. The description adds significant semantic value by explaining specific usage of the 'expand' parameter ('on the event navigation property'), transforming the generic schema description into actionable guidance for calendar integration.

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 specifies getting 'eventMessage object' properties, which is precise about the resource type, but creates ambiguity since the tool name is 'get-mail-message' (suggesting general mail). It doesn't clarify if this works for all messages or only calendar event messages, nor does it distinguish from sibling list-mail-messages.

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?

Provides specific guidance on using the $expand parameter to retrieve associated calendar events, which is valuable. However, it lacks explicit when-to-use guidance versus list-mail-messages (for bulk) or get-mail-attachment (for content), and doesn't mention prerequisites like messageId format.

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