Microsoft 365 MCP Server

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

Annotations correctly mark this as destructive. The description adds that messages are 'saved in the Sent Items folder,' which is valuable behavioral context. However, it fails to clarify what happens to the original draft (presumably deleted) or acknowledge that the claimed 'send new message' capability is unsupported by the schema.

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?

Four sentences are appropriate length, but the final sentence 'Alternatively, send a new message...' does not earn its place—it describes unsupported functionality and sows confusion. Structure is logical but undermined by this factual error.

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?

Description covers draft types and destination folder (Sent Items), providing reasonable context for a send operation. However, it lacks return value description (no output schema exists) and leaves the false 'new message' claim uncorrected, creating a significant gap in accurate behavioral understanding.

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%, establishing a baseline of 3. The description adds crucial semantic context by specifying the messageId refers to an 'existing draft message' (which could be new/reply/forward types), clarifying the parameter's purpose beyond the generic schema description 'Path parameter: messageId'.

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 primary purpose 'Send an existing draft message' is clear, but the final sentence 'Alternatively, send a new message in a single operation' is misleading. The input schema only accepts a messageId string, confirming this tool cannot send new message content inline, contradicting the claimed alternative functionality.

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 explicit guidance on when to use this versus sibling send-mail. The 'alternatively' clause conflates this tool's scope with send-mail, potentially causing the agent to incorrectly select this tool when creating a new message from scratch (which requires send-mail). No mention that drafts must be created first using create-*-draft tools.

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