whatsapp_set_chat_ephemeral

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=true. The description adds useful behavioral context beyond that: all participants see the change, new messages follow it, and the call returns a success confirmation. It does not mention required permissions, but for this simple mutation it is helpful.

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?

The description is three sentences, front-loaded with the action, then the side effect, then the return value. Every sentence earns its place and there is no redundancy.

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 simple two-parameter mutation with full schema coverage and annotations, the description covers what the tool does, the available timer values, the visible effect on participants and new messages, and the return behavior. No output schema exists, so stating the success confirmation is a useful completion.

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%, so the schema already documents chatId and expiration. The description expands the expiration enum values into human-readable durations ('24 hours, 7 days or 90 days'), which adds slight meaning, but it leaves chatId semantics to the schema. Baseline 3 applies when the schema does most of the work.

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 states a specific verb and resource: 'Set the disappearing messages timer for a chat,' and enumerates the exact timer states. It is clearly distinguishable from sibling tools like whatsapp_set_group_announce or whatsapp_mute_chat because it targets per-chat ephemeral messaging.

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?

Usage is implied by the action name and options, but there is no explicit guidance on when to use this tool versus alternatives or any preconditions. For a simple setter this is minimally adequate, but it stops short of stating when-not or naming related tools.

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