browser_fill

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

With no annotations, the description carries the full transparency burden. It discloses one safeguard—'without exposing passwords'—but omits important behavioral traits such as whether existing content is cleared by default (clearExisting=true) or how masking is controlled (maskValueInResult). For a mutating browser tool, this is insufficient.

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 redundant words. It directly states the action and target, and the security note is concise rather than verbose.

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 five parameters, no output schema, and no annotations, the one-sentence description is far from complete. It does not explain the purpose of clearExisting or maskValueInResult, expected return behavior, or when this tool is appropriate relative to other browser-interaction siblings.

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 20% (only sessionId has a description), so the description must compensate. It adds some meaning by specifying the target element types, but it does not explain selector format, clearExisting semantics, or maskValueInResult behavior, leaving most parameters semantically vague.

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 the specific verb 'Fill' and identifies the resource as 'an input, textarea, or contenteditable element,' clearly conveying what the tool operates on. It distinguishes itself from sibling tools like browser_click or browser_select, which perform different actions.

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 guidance is provided about when to use this tool versus alternatives such as browser_select or browser_press_key, nor are any prerequisites, exclusions, or complementary tools mentioned. The usage context is only implied by the tool name and description.

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