lip_sync

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

No annotations provided, so description carries the burden. It discloses the tool is free, renders nothing, and details the response contents (spritesheet URL and row with character_id). Adds useful context beyond a simple 'get' operation, though it doesn't discuss error conditions or rate limits. Sufficient transparency for a read-only tool.

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 that are front-loaded with the core purpose and value proposition. The first sentence explains what it returns; the second clarifies when to use it and the two parameter modes. Every sentence earns its place with no fluff.

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?

No output schema exists, so the description explains the return format (frame-by-frame plan, mouth positions, durations, text progress, spritesheet URL). It covers both usage modes and the distinction from talking_gif. For a tool with 6 params and no output schema, this is a complete and self-contained description.

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% with descriptive parameter docs. The description adds value by clarifying the output difference between character_id (response carries spritesheet URL/row) and viseme_count (preset without character), and notes mutual exclusivity. This goes beyond the schema's basic field semantics.

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?

Clearly states it gets a frame-by-frame lip-sync plan for a line of text, specifying mouth position, duration, and text progress. Distinguishes itself from talking_gif by noting it's free, renders nothing, and is intended for game engines. Specific verb and resource with a clear scope.

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 instructs to use this instead of talking_gif when animating in a game engine and driving the mouth yourself. Also explains the two modes (character_id vs viseme_count), providing clear selection criteria. No ambiguity about when to use.

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