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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description still earns credit by adding the access requirement that the caller must hold the private organizer link containing '/m/', which is real behavioral context not present in the annotations.

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 short sentences, front-loaded with the usage trigger, then the requirement, then the non-mutation note. The closing 'Does not change the calendar' largely restates readOnlyHint/destructiveHint=false, which is a small redundancy but also a useful plain-language confirmation.

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?

This is a one-parameter read tool with a full output schema, so the description need not explain return structure, yet it still sketches the payload. The usage trigger, link requirement, and non-mutation guarantee cover everything needed to invoke it correctly.

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% and the single parameter is fully documented with a format example. The description repeats the 'private organizer link (contains /m/)' hint, which the schema already conveys via its example URL, so it adds little meaning beyond the structured field.

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 names a specific verb and resource ('see a group calendar they made') and enumerates what comes back: events with numbers, next dates, and subscribe links. It clearly reads as the retrieval counterpart to create_group_calendar and update_group_calendar, but it never names those siblings explicitly.

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?

It gives an explicit selection condition ('when the organizer wants to see a group calendar they made') and a prerequisite ('needs the private organizer link'). It stops short of naming a wrong-tool condition or pointing to an alternative for non-organizers, so it is clear context without full routing.

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