list_calendars

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds only the scope ('all calendars the user has access to') and return format ('JSON array'). No mention of pagination, ordering, or whether deleted calendars are included, but with strong annotations and an output schema present, the bar is lower.

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, zero wasted words. The first sentence states the core purpose, and the second clarifies the return format. Nothing extraneous.

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 zero-parameter read-only list tool with a strong annotation set (readOnlyHint, idempotentHint, destructiveHint all set appropriately) and an output schema present, the description is complete enough. It communicates scope and return type. Could add return-shape details, but the output schema likely covers that, and the tool is simple.

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?

There are 0 parameters and no input schema elements, so the description doesn't need to explain parameters. The description does state that it returns a JSON array, which adds value beyond the schema for the return type. With 0 parameters, a baseline of 4 is appropriate.

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 clearly states the verb ('List') and resource ('all calendars the user has access to'), making the purpose clear. It distinguishes from siblings like get_calendar and list_events by specifying it returns all calendars, not a single one. It could further differentiate by mentioning it's the collection-level tool for calendar enumeration.

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 implies this is the tool for enumerating all calendars but provides no explicit when-to-use vs alternatives guidance. It doesn't mention 'use this to discover available calendars before querying events' or any exclusion criteria. There's no reference to sibling tools for comparison.

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