Microsoft 365 MCP Server

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

Annotations already mark this as destructive (destructiveHint:true). Description confirms it creates resources, adding no additional behavioral context about side effects, rate limits, or failure modes (e.g., message not found). The truncated sentence about attachment types adds confusion rather than transparency.

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?

First sentence front-loads purpose efficiently, but the description ends with an incomplete thought ('All these types...') that appears truncated. This structural breakage creates ambiguity about attachment polymorphism without delivering useful 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?

For a destructive mutation tool with nested object parameters and no output schema, the description lacks critical context: error scenarios, size limits (despite size field in schema), or the relationship between messageId and the attachment operation. The incoherent trailing sentence wastes space without adding value.

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 75% (high), with body properties and flags adequately documented in schema. Description adds no parameter semantics, but baseline 3 is appropriate given schema carries the load. No compensation needed for the well-described messageId and body parameters.

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?

States basic verb ('create') and resource ('Attachment') but lacks scope clarity on whether this attaches to existing messages or drafts. The trailing sentence about 'types derived from attachment resource' is incoherent/fragmented, detracting from clarity. Does not differentiate from siblings like get-mail-attachment.

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 on when to use this versus creating a draft with attachment, or prerequisites like message existence. No mention of inline vs regular attachment use cases despite schema supporting isInline flag.

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