fill_input

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

No annotations provided, so the description carries the full burden. It discloses the behavioral traits: uses native value setter, dispatches input/change to reach framework onChange handlers, returns ok:false honestly on failure (does not fake success). This is meaningful behavioral context beyond schema.

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?

Compact and dense, with a worked example up front and failure behavior noted. Slightly dense/technical (Chinese prose) but each sentence earns its place. No wasted words, though formatting could be cleaner.

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 3-param mutation tool with no annotations and no output schema, the description covers purpose, success/failure semantics, framework behavior, and fallback path. The 'tab' parameter remains undocumented, which is a genuine gap for a 3-parameter tool. Otherwise quite 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. It provides an example invocation filling sel='#email' with text='a@b.com', which clarifies sel and text semantics. However, the third parameter 'tab' is not documented at all, and 'sel' selectors' syntax/format is only implied by the example. Partial compensation.

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?

Clear verb+resource: fills an input element via framework-aware value setting. The description explicitly distinguishes from type_text (which uses Input.insertText and often bypasses framework setters), and mentions click_selector + type_text as the alternative for custom components. Specific and differentiates from 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?

Explicitly states when to use this (React/Vue controlled components where type_text fails) and when not to (custom components needing real typing → use click_selector + type_text). Also notes failure conditions (non-input/textarea/contenteditable → ok:false). Strong when/when-not guidance.

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