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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety and scope are covered. The description adds the genuinely useful behavioral facts that the result is a reference of accepted ids for two other tools and that defaults are included, but says nothing about freshness, caching, or ordering beyond that.

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?

A single sentence fragment with no filler, and the three id categories are stated up front. It loses a point because the fragment lacks a verb and reads awkwardly as a standalone definition, making the agent supply 'lists' from 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 parameters, an output schema covering the shape of the return, and annotations covering safety, the description only needs to explain purpose and consumers, which it does. A note on whether the values are static or environment-specific would close the remaining gap.

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 the baseline is 4 and there is nothing for the description to disambiguate. Its mention of face/voice/brain ids is about return content, not inputs, which is correct for a parameterless call.

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 names the exact resource: the face, voice, and brain ids accepted by create_nod and update_nod, plus their defaults. That is a specific content statement that separates it from siblings like list_faces or get_nod, though it is written as a noun phrase without a verb, so the 'list' action comes only from the tool name.

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?

By naming create_nod and update_nod as the consumers of these ids, the description implicitly tells an agent when to call it: before constructing those calls. It never states that guidance explicitly, nor does it contrast with list_faces or clarify whether the values are static, so usage is inferred rather than prescribed.

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