fill

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

Annotations declare readOnlyHint=false, implying mutation, but the description says nothing about whether the existing value is cleared or appended, whether input/change events fire, or that it requires a valid uid from a live page. The one useful behavioral nuance (select options) is also covered by the schema's value description.

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?

A single tight sentence with the action front-loaded and no filler. It is efficient, though the brevity comes at the cost of the usage and behavioral detail an agent would benefit from.

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 DOM interaction tool with no output schema and minimal annotations, the description omits prerequisites (element discovery via snapshot), what happens to pre-existing values, and the effect on the page. Important context for correct invocation is missing.

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%, so all four parameters including the checkbox/radio 'true'/'false' convention and includeSnapshot are documented in the schema. The description adds no parameter detail beyond that, so the baseline of 3 applies.

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 concrete action (type text / select an option) and names the target resources (input, text area, <select>). However, it does not distinguish itself from close siblings like fill_form and type_text, which an agent must choose between for similar tasks.

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?

There is no guidance on when to use this instead of type_text or fill_form, nor any note that the target element must first be located via a page snapshot. The agent is left to infer the selection criteria entirely.

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