Calendar

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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds the default date-range behavior, which is genuine context, but says nothing about auth requirements, pagination, or coverage limits of the fetch.

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?

Three tight sentences, front-loaded with the core action, then the default behavior, then the alternate modes. No filler and every clause carries 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?

With no output schema, the description should carry more of the return-shape burden, but it names the available modes and the compact summarization behavior. It leaves the relationship between 'date' and the 'start'/'end' range pair implicit, a minor gap for a 6-param multi-mode tool.

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 100%, so every parameter is already documented in the schema (including what 'compact' omits). The description only adds that date params default to today, which is minor meta-context; baseline 3 is correct.

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 a specific verb and resource ('Fetch the user's Microsoft 365 calendar events') and enumerates two secondary modes (list calendars, drill into an event). It is clear against generic tool names, but it never names the calendar-adjacent siblings (ms_schedule) it could be confused with, so it stops short of full sibling differentiation.

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?

Gives one useful usage rule ('Defaults to today if no date params given') and hints at alternate modes, which is more than nothing. However, it never states when to prefer this tool over ms_schedule or ms_brief, nor when to use which mode, leaving usage to inference.

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