Microsoft 365 MCP Server

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

Reveals behavioral traits beyond annotations: states message is 'saved in the Sent Items folder', describes HTTP 400 error responses for validation failures, notes base64 encoding requirement for MIME format, and clarifies server-side handling of attachments/HTML. Annotations indicate destructiveness but description adds operational context.

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?

Well-structured with clear JSON vs MIME sections and bullet points, but contains redundancy between main description and TIP section (repeats comment field behavior and toRecipients requirement). The dual-format explanation is necessary complexity, though the TIP could integrate more smoothly.

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?

Comprehensive coverage for a complex dual-mode tool with nested objects. Addresses both JSON and MIME formats, error conditions, destination folder behavior, and distinguishes from draft creation. No output schema present, but description adequately covers input complexity and behavioral outcomes.

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?

With 75% schema coverage, description adds critical mutual exclusivity constraints not captured in schema: conflict between comment vs body property, and between toRecipients parameter vs toRecipients property within message. Also clarifies base64 encoding requirement for MIME body and that toRecipients is effectively required.

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?

Clear specific verb ('Forward') + resource ('message') + scope ('using either JSON or MIME format'). Explicitly distinguishes from sibling tool create-forward-draft by stating 'Alternatively, create a draft to forward a message, and send it later', clarifying this sends immediately while the sibling creates a draft.

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?

Explicitly names alternative workflow ('create a draft to forward a message, and send it later'). Provides detailed when-to-use constraints: mutual exclusivity rules for comment/body and toRecipients locations, HTTP 400 error conditions for invalid combinations, and format-specific requirements (base64 for MIME).

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