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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds the behavioral scope 'upcoming,' which tells the agent it returns future events only, but it does not mention timezone handling, default calendar behavior beyond what the schema states, or any limitations. This adds some context without being rich.

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 a single concise sentence that immediately communicates the tool's purpose. It is front-loaded and contains no fluff or redundant 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 output schema exists, return values are already documented. However, the presence of a similarly named sibling 'list_calendar_events' creates ambiguity that the description does not resolve. For a simple read-only tool with rich schema, the description is mostly adequate but lacks the contextual differentiation needed for confident tool selection.

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?

The input schema covers 100% of the parameters with descriptions for 'days,' 'limit,' and 'calendar,' so the schema already explains their meaning. The description provides no additional parameter semantics beyond the schema, which meets the baseline but does not elevate it.

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 uses the specific verb 'List' with the resource 'upcoming calendar events from your Microsoft 365 / Outlook calendar,' clearly indicating the tool's function. However, it does not differentiate itself from the sibling tool 'list_calendar_events,' which appears to serve a similar purpose, so it misses the opportunity to distinguish among alternatives.

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?

There is no explicit guidance on when to use this tool versus alternatives such as 'list_calendar_events' or other calendar-related tools. The description only implies usage for retrieving upcoming events, but no contexts, exclusions, or alternative recommendations are provided.

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