set_font_size

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

No annotations exist, so the description carries full burden. It discloses that changes persist to 'appearance.fontSize' and that a 'font-size-changed' event is broadcast for immediate UI update. This provides clear behavioral insight.

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 sentences, each substantive. First defines purpose and range, second gives real-world analogy, third details persistence and event. No unnecessary words.

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?

Given the simple parameter and no output schema, the description fully explains the tool's action, effects, and parameter meaning. No gaps or missing information.

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%, but the description adds value by stating the default value (100) and the context of mirroring UI buttons. This enhances understanding beyond the schema's 'Zoom percentage. Clamped to 70-150.'

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 specific verb 'Set' and clearly identifies the resource as 'UI font-size zoom factor' with a range of 70-150%. This distinguishes it from sibling tools, none of which relate to font size.

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 mentions it mirrors the A- / A+ buttons, providing context, but does not explicitly state when to use this tool versus alternatives or when not to use it. Usage is implied but not fully guided.

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