Set disappearing messages

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

Annotations already cover the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the description's contribution is the added behavioral note that 'Messages already stored in wuapi are kept' — a genuinely useful disclosure about scope of effect. It's consistent with the annotations and doesn't need to restate them, though it says nothing about permissions or how existing chats are affected by a default change.

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?

One dense sentence that front-loads the on/off action and then resolves the two scopes; the retention caveat is appended without padding. Minor awkwardness from packing three clauses with commas, but no sentence is wasted.

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?

With no output schema and annotations covering safety, the description addresses the key ambiguities an agent needs: what the two modes mean, which parameter selects them, and that stored messages persist. Only the effect of changing the account default on existing chats is left implicit.

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 every parameter including the durationSeconds enum and its meaning is already documented in the schema. The description restates the chatId-optional behavior that the schema already explains, adding little beyond the baseline. It does not clarify the duration values or account resolution, so 3 is the correct baseline.

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?

Specific verb+resource: turns disappearing messages on or off, and it clearly distinguishes the two scopes (per-chat with chatId vs. account default). It doesn't explicitly name or contrast a sibling, but the scope qualifier makes the purpose unambiguous against neighbors like mute_chat or archive_chat.

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?

States the condition that selects each mode: pass `chatId` for one chat, omit it to set the account default that new chats inherit. Clear context for when to use which variant, though it offers no exclusions or prerequisites and no alternative tool routing.

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