smart_fill

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

With no annotations provided, the description carries the behavioral disclosure burden. It discloses meaningful behavioral traits: label matching is fuzzy and case-insensitive, no snapshot is needed, and values go through the same clearing logic as fill so email/number fields replace rather than append. It does not describe error handling or effects of within/submit_label, but the core mutating behavior is transparent.

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?

Two dense sentences carry the essential information with no filler. The primary behavior and distinguishing constraint are front-loaded, and the comparative clause about fill is placed at the end without bloating the description.

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 tool with a simple required fields_json parameter and clear schema descriptions, the description adequately covers the operation and key behavioral nuances. It could mention return values or what happens when no label matches, but those are minor gaps given the schema richness and simple scope.

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 input schema already documents all three parameters with 100% coverage, so the baseline is 3. The description adds high-level semantics about label matching and value clearing, but it does not add per-parameter details beyond what the schema's property descriptions already provide.

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: fill form fields by their LABEL text, with fuzzy and case-insensitive matching. It also immediately contrasts itself with 'instead of refs' and 'no snapshot needed', which clearly sets it apart from tools like fill that rely on refs or snapshots.

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 gives clear context for when to use smart_fill: when you know label text and do not have refs or a snapshot. It connects behavior to fill by noting the same clearing logic. However, it does not explicitly exclude or compare against fill_form or find_by_label, so the guidance is clear but not exhaustive.

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