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

Annotations provide no positive safety profile (readOnlyHint false, destructiveHint false, etc.), so the description carries the burden of behavioral disclosure. It does add useful context like automatic emotion detection from text and the returned animated view, but it doesn't mention any persistent side effects or prerequisites, leaving some ambiguity.

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 compact and well-structured: it leads with the core action, explains inputs and emotion handling, and closes with the return value. No wasted words, though it could be slightly more explicit about output format.

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 tool with 3 well-documented parameters, no output schema, and clear sibling differentiation, the description covers the essential usage: what it does, how to invoke it, and what to expect in return. It lacks minor details like error conditions or whether the persona must already exist, but these are not critical.

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 each parameter already has a clear description in the schema. The description adds the behavioral context (emotion auto-detection) but does not provide additional semantic detail about the parameters themselves, so a baseline of 3 is appropriate.

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 action (perform a reply) on a specific resource (persona), detailing the behavior (lip-sync, facial expression, body gesture). It clearly distinguishes this from sibling tools like create_agent_persona or get_agent_persona, which focus on persona lifecycle rather than speech.

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?

The description explicitly frames this as 'the turn-by-turn embodiment hook', which signals when to use it (each turn the agent speaks). It does not explicitly list alternatives or exclusion conditions, but the sibling context makes the intended use clear enough.

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