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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, but the description adds substantial operational detail: the source of available fonts, the refusal behavior, and the exact/contains/close_matches resolution logic for family names. It also describes what is returned in the without-family and with-family cases.

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?

The description is front-loaded with purpose and then moves through validation, return behavior, and usage guidance. It is appropriately sized, though the long matching-logic sentence is dense and the standalone 'Read-only' sentence largely repeats annotation information.

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?

There is no output schema, but the description explains the relevant return values: families with style counts, or style details such as style name, weight, and italic when a family is specified. Combined with annotations covering safety and schema covering parameters, an agent has enough information 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 description coverage is 100%, so the schema already documents limit, family, and intent. The description adds meaningful semantics for family, explaining exact-match precedence, case-insensitive contains matching, fallback to close_matches, and the differing return shapes with and without family.

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 states a specific verb and resource: listing font families available to a design, scoped to Kalpana's global library plus workspace uploads. The purpose is unambiguous and distinct from sibling tools such as list_shaders, list_pages, or find_images.

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?

It gives clear usage context by saying to call it before setting font_family or font_style on text, and explains that fonts outside the list are refused. It does not state when not to call it or name alternatives, but no obvious alternative tool exists.

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