fill_form

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

The readOnlyHint=false annotation already signals a mutating operation, and the description aligns by describing 'fill out.' It adds some behavioral context by emphasizing batch execution in 'one call' and claiming reliability, but it does not disclose partial-failure behavior, side effects, or response semantics.

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 compact and well-structured: the first sentence defines scope, the second is a high-value routing directive, and the third is a concrete example. Every sentence earns its place with no fluff or redundancy.

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 batched form-fill tool, the description provides purpose, usage precedence, element coverage, and a worked example, while the schema covers all parameter meanings. It lacks only explicit fallback conditions and direct response details, but those are minor given includeSnapshot is already documented in the schema.

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 the schema already documents pageId, elements, and includeSnapshot fully. The description's example ('username, password, and check Remember Me') adds a helpful real-world mapping, but it does not add meaningful parameter syntax beyond what the schema provides.

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 states a specific verb ('fill out') and a specific resource ('multiple form elements') and enumerates the element types it covers. It also distinguishes itself from sibling tools by explicitly contrasting with 'fill' or 'click' calls.

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 an explicit, strong usage directive: 'ALWAYS prefer this tool over multiple individual fill or click calls when interacting with forms,' and provides a rationale (faster, more reliable, fewer turns). It does not explicitly state when to fall back to single-element fill/click, so a small exclusion gap remains.

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