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

Adds behavior the annotations don't convey: the indicator auto-expires after ~8 seconds, must be re-called for longer work, and costs nothing ("Free"). This is consistent with idempotentHint=true and destructiveHint=false; the transient side effect also squares with readOnlyHint=false.

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?

Two short clauses with zero waste: the effect and duration come first, the continuation advice second. Nothing is padded or restated from the title.

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 one-parameter, no-output tool, the essentials (effect, lifetime, refresh pattern, no cost) are covered. Minor gaps remain around whether the conversation must be open or what happens if it has ended.

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 0% and the description never mentions conversation_id, so it does not compensate for the gap. The single parameter is self-explanatory by name, which limits the harm, but no added meaning is supplied.

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 and effect: shows a "typing" indicator to the visitor, with a concrete duration (~8 seconds). That is clearly distinct from sibling tools like chat_reply or chat_wait, though it never names them.

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 a clear usage trigger: call it while working on a longer answer, and call again to extend the indicator. It does not state when NOT to use it or name alternatives, but the guidance is concrete enough to act on.

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