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

Annotations already signal read-only and non-destructive behavior. The description adds useful operational context: authenticated-user scope, subscribed/shared calendar inclusion, default ±31 days, maximum 366-day window, and result datetime timezone. No mention of pagination or sort order, so slightly less than full 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?

Four tight sentences: purpose and scope first, then defaults, limits, and filters. No fluff, no redundancy beyond schema-required grounding, and the most decision-relevant information is front-loaded.

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 a read-only annotation and an output schema present, the description covers scope, constraints, timezone behavior, and filter options well. It does not mention pagination or result limits, but that gap is minor given the schema richness.

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 covers 100% of parameters with descriptionsants. The description largely restates them, though it adds useful context like the default time window and max span. Baseline 3 is appropriate since the schema carries most parameter meaning.

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 a specific verb and resource—'List events in a time window'—which immediately conveys the core action and distinguishes it from write tools like create_event. It also clarifies the data scope ('for the authenticated user', including subscribed/shared calendars), making the purpose unambiguous.

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 clearly conveys when to use it: listing events within a time window, with optional filters. However, it does not explicitly compare against siblings like get_event or get_free_slots, so an agent must infer the differentiation rather than being told.

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