Microsoft 365 MCP Server

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

Annotations indicate destructiveHint=true and readOnlyHint=false, which the description aligns with by describing a send operation. The description adds valuable behavioral context beyond annotations: it explains that MIME format saves to Sent Items, mentions file attachment handling with JSON, and warns against guessing email addresses. However, it doesn't cover rate limits, authentication requirements, or error behaviors that would be helpful for a destructive operation.

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 description is moderately concise but could be better structured. It starts with the core purpose but includes a somewhat tangential tip about backend steps ('see here') that doesn't add immediate value. The critical tip about not guessing email addresses is important but disrupts flow. Sentences are mostly purposeful, but the structure could be more front-loaded with essential information.

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 (destructive operation, 3 parameters with nested objects, 67% schema coverage, no output schema), the description is somewhat incomplete. It covers basic usage and warnings but lacks details on error handling, response format, permissions needed, or limitations (e.g., attachment size). For a tool with destructiveHint=true and rich input schema, more behavioral and operational context would be beneficial.

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 67%, and the description adds minimal parameter semantics beyond the schema. It mentions that JSON format allows file attachments and that MIME format affects Sent Items, which relates to the 'body' parameter's content. However, it doesn't explain the purpose of 'includeHeaders' or 'excludeResponse' parameters, nor does it clarify the complex 'body.Message' structure. The description provides some context but doesn't fully compensate for the schema's gaps.

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 clearly states the tool's purpose: 'Send the message specified in the request body using either JSON or MIME format.' It specifies the verb ('send') and resource ('message'), but doesn't explicitly distinguish it from sibling tools like 'create-draft-email' beyond mentioning draft creation as an alternative. The purpose is clear but sibling differentiation is incomplete.

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?

The description provides clear usage context: it mentions when to use JSON vs MIME format, references an alternative ('create a draft message to send later'), and includes a critical tip to use 'list-users' for finding email addresses. However, it doesn't explicitly state when NOT to use this tool versus alternatives like 'create-draft-email' or other email-related tools, leaving some ambiguity.

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