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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, so the trailing 'Read-only' earns no credit. The description does add genuinely useful context — that results include weights per family and that names are validated against layout rules — but says nothing about result volume, pagination, or how `limit` behaves.

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 compact sentences: what it returns, why the names matter, and safety. Front-loaded and free of filler.

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?

An output schema exists, so return shape needn't be described, and the description covers the important cross-tool relationship (family names consumed by layout rich-text fields). The only real gap is that two of the three parameters go unexplained in both schema and 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 only 33% (only `query` is documented). The description never mentions `projectId` or `limit`; the scoping of results to a project is only implied by the phrase 'project-uploaded'. With the schema under-documented here, the description should have compensated and does not.

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?

Specific verb + resource ('Lists ... font families') with explicit scope: built-in, Google, and project-uploaded families, plus their available weights. An agent can immediately tell this is the font-catalog tool and no other sibling covers font enumeration.

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?

The sentence 'Layout validation accepts these exact family names in rich-text font fields' tells the agent why and when to call it (to obtain valid family names before setting font fields). No explicit exclusions or alternative tools are named, so it stops short of a 5.

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