List fonts

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the dual behavior (listing built-ins AND resolving a name against system fonts), which is genuinely useful. However, it doesn't disclose the return format, behavior when family is invalid/not found, or any side effects, though as a read-only listing tool the stakes are relatively low.

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?

One well-formed sentence that conveys purpose and context efficiently with zero waste. It is appropriately front-loaded and compact; no redundant phrasing or 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?

For a simple read-only listing tool with 1 optional parameter, 100% schema coverage, and no output schema, the description is reasonably complete. It covers both behaviors (listing and resolution) and ties to the create_letter use case. The main gap is not describing return values, but the tool's simplicity keeps this from being a major deficiency.

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%, so the schema already documents the family parameter as a font family or .ttf path. The description adds the semantic connection that resolution is against installed system fonts and relates to create_letter embedding, which adds modest value beyond the schema. A baseline 3 is appropriate when the schema carries the parameter documentation load.

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 uses a specific verb-list combined with a clear resource (font families) and adds the resolution behavior against system fonts. It distinguishes itself from siblings by tying it to create_letter embedding, though it doesn't explicitly differentiate from other listing tools like list_locales or list_profiles beyond the subject matter.

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 description implies the usage context ('so you can check what create_letter would embed'), which gives some when-to-use guidance. However, it doesn't explicitly state when NOT to use it, mention that the family parameter is optional, or clarify alternatives among sibling tools.

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