fill_element

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

With no annotations, the description must carry the behavioral disclosure burden, but it only states the literal filler action. It does not clarify whether existing text is replaced, whether input events are triggered, how indexing works (though schema explains), or any side effects. This leaves significant behavioral ambiguity.

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 description is a single, front-loaded sentence with no unnecessary words. It directly opens with the verb and includes the key selector concept, making it highly efficient and scannable.

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 tool has 5 parameters including index, submit, and connection_id, and no output schema, the description is too thin. It ignores the richer behavioral context (e.g., pressing Enter, multiple matches) and provides no guidance for how to use the tool effectively in automation scenarios.

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%, so the baseline is 3. The description itself adds no parameter semantics beyond what the schema already documents — it merely restates the 'text' parameter. Since it does not introduce additional meaning, a 3 is appropriate.

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 clearly states the action ('Fill text'), the target ('an input element'), and the locating mechanism ('matching the CSS selector'). It distinguishes from siblings like click_element by specifying the fill action, making the purpose unambiguous.

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?

No usage guidance is provided — the description does not mention when to prefer this tool over query_elements, click_element, or other interaction tools. It lacks any context about prerequisites, typical workflows, or alternatives, leaving the agent to infer usage.

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