list_speech_voices

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

readOnlyHint=true already declares this as a safe read, and the description adds value on top: the ranking semantics ('best first'), the fact that each entry shows its license, and the naturalness caveat for Piper voices. These are behavioral details the annotation cannot convey. It stops short of 5 because it doesn't say how many voices typically appear or what a license entry looks like.

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 sentences, front-loaded with the resource and ordering before the licensing caveat. Every clause carries information: ranking, naturalness, license visibility, and release eligibility. No filler or restatement of the name.

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 only readOnlyHint, the description does the work of describing what comes back (ranked voices with licenses) and how to judge the result for release use. It is nearly complete; the only minor gap is not hinting at result size or the fallback when Piper voices are absent.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; per the zero-parameter baseline this is a 4. No misleading parameter language is present.

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?

Names the exact resource ('text-to-speech voices on this computer') and its ordering ('best first'), and ties it to the sibling tool it feeds ('add_robot_vocal's voice'), so an agent can tell it apart from list_installed_fx, list_sounds, or list_scales without opening the schema. The listing verb is only implied by the noun phrase rather than stated outright, keeping it short of a perfect 5.

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?

Explicitly frames the context of use (picking a voice for add_robot_vocal) and gives a concrete eligibility rule ('only public domain, CC0 or CC BY ones may go in released music'), which is real decision guidance. It does not name an alternative tool or state when-not to call it, so it stops at a strong 4.

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