ass_match_font

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

With no annotations, the description carries the full burden and does disclose a real behavioral trait: that the first candidate is the face used, and that a family mismatch means the subtitle renders in a substitute. It stops short of stating whether the call is read-only or has any side effects, but the substitution semantics are genuinely useful context.

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 purpose is front-loaded in the first sentence and the substitution note adds value. The trailing return-field list is largely redundant with the existing output schema, slightly diluting an otherwise tight definition.

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 query tool with an output schema, the return explanation is unnecessary but harmless, and the substitution behavior is covered. The absence of any usage routing against the many font-related siblings and the undocumented boolean parameters leave it only minimally complete.

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 0%, so the description must compensate, and it partially does by naming `family`, `bold`, and `italic` in prose and tying them to the resolution behavior. It does not explain the boolean defaults (both false) or how bold/italic alter candidate ordering, leaving a gap against 0% coverage.

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+resource framing ("What fontconfig actually resolves for `family`") that tells an agent exactly what the tool computes. It differs from siblings like ass_check_font_substitution by emphasizing the actual resolution result. However it never explicitly contrasts against those siblings.

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?

There is no explicit when-to-use / when-not-to-use guidance and no named alternative, despite close siblings such as ass_check_font_substitution, ass_font_coverage, and ass_list_fonts. Usage is only inferable from the one-line purpose statement.

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