Say (on a call)

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

Beyond the annotations, the description discloses that playback is non-blocking, that the result includes anything the user said meanwhile, and that tool output does not render on screen. These are important behavioral traits not represented in the annotations.

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?

Purpose and routing are front-loaded, and the bullet structure is scannable. However, the description runs long for a one-parameter tool and repeats the on-screen reply warning across two bullets, so it is useful but not maximally concise.

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?

It covers when to use the tool, the alternative, playback and return behavior, speech composition constraints, and the on-screen reply caveat. With no output schema, it adequately explains what the result includes and what the agent must do to avoid a silent interaction.

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?

Although the schema fully covers the single text parameter, the description adds concrete semantics: 1–3 short sentences, under about 40 words, plain words only, no markdown or URLs, describe code rather than reading it, and ask one question at a time. This is substantial meaning beyond the schema's 'plain, conversational text.'

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: speak supplied text during a call and return immediately. It also names the sibling alternative, speak_and_listen, for use outside a call, so an agent can distinguish it from related voice tools.

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?

It explicitly restricts usage to during a call and directs the agent to speak_and_listen otherwise. Additional guidance covers how to compose spoken text, leaving little ambiguity about when and how to invoke it.

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