page_fill

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

With no annotations provided, the description carries the behavioral burden. It discloses that the value is set directly rather than via key events, and that it 'fires input/change events like real edits,' which is important for agent reasoning about side effects. This is meaningful added context, though it could mention more about limitations or error behavior.

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, focused sentence that front-loads the core action and then adds the most important behavioral detail. There is no redundancy, filler, or unnecessary technical jargon.

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's moderate complexity, the description covers the core behavior, the reason to use it over an alternative, and relevant event behavior. The main gap is parameter-level detail, but the required parameters are standard across siblings and mostly inferable from names.

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 only 25% (only selector has a description). The description does not explain session_id, page_id, or text semantics beyond the implied 'value' of an input. While parameter names are somewhat self-explanatory, the description does not compensate for the low schema coverage.

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 tool's function: 'Set an input's value directly (form fill)'. It uses a specific verb and resource, and differentiates itself from key-event typing, which maps to sibling page_type. An agent can tell this tool apart from related 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?

It gives explicit context for when to use this tool: 'Works where key-event typing hits engine bugs.' This implies page_type as the alternative and identifies a clear condition for choosing page_fill. It doesn't state an explicit when-not-to-use list, but the guidance is clear.

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