fill

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

With no annotations, the description carries the burden of disclosing behavior. It transparently states that existing content is cleared, which is a key side effect. However, it does not disclose other behaviors such as event firing, waiting for element visibility, or compatibility with different form field types, leaving some 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 two short sentences, front-loaded with the primary action and immediately followed by the critical clearing behavior. Every word earns its place with no fluff or repetition.

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 is a simple form-filling operation with all parameters documented in the schema and no output schema to explain, the description covers the essential behavior (clearing and filling). It could be slightly more complete by noting whether it triggers input/change events or waits for visibility, but the current level suffices for a basic tool.

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 schema already documents all parameters ('selector', 'value', 'timeout'). The description adds minimal value by implying 'given value' refers to the value parameter and that clearing happens before filling, but it does not provide additional meaning beyond the schema descriptions.

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 ('Fill') and resource ('a form field'), clearly distinguishing it from siblings like 'type' (which implies keystroke-level input) and 'select' (which implies choosing from options). The additional behavior 'Clears existing content first' reinforces its purpose as a full replacement operation.

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 implies usage context: use this when you want to set a field's entire value, as evidenced by 'Clears existing content first'. However, it does not explicitly contrast with alternatives like 'type' or 'select', nor mention when not to use it (e.g., for non-input elements).

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