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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description earns credit for going beyond them by naming the required `calendar:read` scope and flagging that human-written text arrives in `untrusted_fields` and must be treated as display-only data rather than instructions — a genuinely non-obvious operational trait.

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?

Two short sentences with no filler, and the scope requirement plus the injection warning are front-loaded. Sizing is appropriate, though the "by day" phrase is too terse to be informative and could be expanded without cost.

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 read-only, three-parameter tool with no nested objects and no output schema, the description covers the two things an agent could not infer elsewhere: authorization scope and untrusted-content handling. The remaining gap — date format and result granularity — is real but moderate given how simple the surface is.

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 0% for all three required parameters, so the description carries the full burden — and it says nothing about `from`/`to` formats (dates vs timestamps, inclusive bounds) or the expected `timezone` identifier form. The only semantic clue is the vague "by day", which does not explain how the range is chunked.

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 states a verb and resource ("Get my calendar by day"), but "by day" is the only hint at how results are grouped and it is never explained. It does not differentiate from close siblings such as list_calendar_events, get_calendar_block, or export_calendar, so an agent cannot tell which calendar read tool this is meant to replace.

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 when-to-use or when-not-to-use guidance and no mention of alternatives, despite a crowded sibling set of calendar readers. The required `calendar:read` scope is stated, which is a useful precondition, but it does not route the agent between tools.

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