calendar_set_calendar

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

No annotations are provided, so the description carries the full burden — and it does disclose the key side effects: hiding does not stop syncing, disabling sync removes events from the device, enabling sync downloads them via a separate tool. It doesn't mention permission requirements or error behavior when the calendar id is unknown.

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 short sentences, front-loaded with the operation and followed by the two most important semantic distinctions. No filler or repetition.

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 no-annotation, no-output-schema settings mutation, the description covers what changes, what the states mean, and the required follow-up call. Minor gap: no statement about failure modes for an invalid calendar id.

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 coverage is 100%, so the schema already defines 'visible', 'sync', and 'calendar'. The description adds genuine meaning by explaining that the two booleans are independent settings with different consequences (hidden vs. synced), which an agent could not infer from the schema alone.

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 (show/hide, toggle sync) and resource (a calendar in the phone's calendar list), and explicitly separates it from event-level operations ('not changes to the events'), which distinguishes it from calendar_update and calendar_events.

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 clear context: use it for phone-level settings, and run calendar.sync_background after enabling sync to actually fetch events. It also excludes event editing. It stops short of fully routing the agent to a sibling for event-level changes by name, hence a 4 rather than a 5.

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