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

Annotations already flag a non-destructive, open-world mutation. The description adds real value on top: the source is the Google Fonts catalog (consistent with openWorldHint), the effect is attaching a source file to the forge, and the return is a pfc-asset:// token — notable since there is no output schema. Gaps remain on failure behavior (unknown family) and whether repeated calls duplicate assets.

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?

Three tight sentences, front-loaded with the action and scope, followed by the integration token and the per-parameter clarifications. No filler or repetition of the schema.

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 3-parameter mutating tool with no output schema and only 33% schema coverage, the description covers purpose, return value, and post-call usage adequately. It leaves edge cases (invalid family, variant format, re-fetch/idempotency) unaddressed but is otherwise sufficient to call the tool correctly.

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 only 33% (only forgeId is documented), so the description must compensate, and it largely does: `family` is defined as the catalog family name with an example ('Roboto') and `variant` is said to default to regular. It stops short of giving the accepted variant syntax (e.g. bold/italic vs numeric weight).

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?

States a specific verb and resource ('Fetch an open-licensed font from the Google Fonts catalog') plus its side effect ('attach it to a forge as a source file'). No sibling tool deals with fonts, and the downstream linkage (pfc-asset:// token, k.text2d rendering) makes the intent unmistakable.

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?

Tells the agent exactly where the result goes: declare the returned token in the part's `fonts:` field, then use it in k.text2d. That is clear contextual guidance for when this tool is needed, but there is no explicit when-not or named alternative for obtaining fonts by other means.

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