Fill input

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

Goes well beyond the readOnlyHint=false and openWorldHint=true annotations by disclosing that existing content is destroyed first, that password and card values are masked in recordings, and that live payment environments cause an outright refusal with a suggested workaround. These are exactly the side-effect and failure-mode facts an agent cannot infer from structured fields.

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, front-loaded with the core action, then the privacy/masking behavior, then the payment-environment restriction. No filler and no repetition of name or title.

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 mutating open-world tool with no output schema, the description covers destructive clearing, credential masking and a hard refusal case. The one meaningful omission is whether input/change/keyboard events are dispatched, which affects subsequent assertions and form submission in an automation context.

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 100%, with selector, text, frame and timeout all documented inline, including the note that an empty string clears the field. The description adds no further parameter-level meaning, which is acceptable given the schema already carries the load, hence the baseline.

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?

States a specific verb pair (clear + fill) and a precise resource set (input, textarea, contenteditable), which cleanly separates it from siblings like click_element, select_option and press_key. The clear-then-fill semantic is stated up front rather than implied.

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?

Provides concrete when-to-use guidance for a contested scenario: card fields are refused on LIVE payment pages, so use the provider's test mode with test cards. It stops short of naming when to prefer siblings (e.g. select_option for dropdowns, click_element for submission), so the element-selection guidance is inferred rather than explicit.

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