Change a group chat

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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context beyond that: the change is broadcast to all participants ("Everyone in the group sees the change") and the platform restriction limits where the mutation applies. It does not say whether removals are reversible or what happens on failure, so it is not a 5.

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 operations, then the platform constraint, then the side effect. Every sentence carries information an agent would otherwise have to guess.

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 destructive mutation with no output schema, the definition covers scope, platform limits and the visible side effect, which is solid. It leaves open what the tool returns on success, how partial failures behave (e.g., invalid phone number), and whether the caller needs to be a group participant — gaps an agent may hit at call time.

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 50%: add_person and remove_person are documented in the schema, while chat_id and rename_to are not. The description maps each operation to its parameter implicitly ("rename" → rename_to, "add or remove a person" → add_person/remove_person), which helps, but adds no format or interaction detail, such as what happens if both add and remove are supplied or what chat_id must look like.

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?

"Rename a group chat, or add or remove a person" names the resource (group chat) and the three concrete operations, so an agent can distinguish it from edit_message or send_message at a glance. It stops short of explicitly naming a sibling it is not, which keeps it out of the top band.

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?

"Works only in iMessage groups, not SMS or RCS groups" is an explicit when-not condition, which is the most important routing constraint for this tool. It does not name an alternative for the SMS/RCS case or explain prerequisites, so it is clear but not complete.

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