design_list_fonts

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

With no annotations, the description must carry the behavioral load; 'List all available' reasonably signals a non-mutating enumeration, and it discloses the returned fields (weights, categories, metrics). However, the hedged 'when available' is never explained, and nothing says whether the list reflects only fonts registered in the current session or is global/cached.

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 front-loaded sentence with no preamble or padding. Every clause (built-in vs custom, returned fields) carries 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?

With no output schema and no annotations, the description does the essential work of describing what comes back (weights, categories, metrics). The remaining gap is the source/scope of the font list and the meaning of 'when available', which an agent may need to know before relying on the results.

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; there is nothing for the description to disambiguate. The description correctly implies the call takes no filtering input rather than suggesting hidden options.

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+resource (list all available fonts) and scopes the resource precisely as built-in system fonts plus registered custom fonts. It implicitly separates itself from design_load_custom_font (registration) and design_get_font_metrics (metrics for a specific font), though it does not name those siblings explicitly.

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?

Usage is only implied: an agent can infer this is the discovery call to run before design_set_text / design_apply_text_style. There is no explicit when-to-use vs when-not-to-use statement, no mention of the alternative design_get_font_metrics for per-font metric lookups, and no note that custom fonts must be registered via design_load_custom_font before they appear.

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