fill_form

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

Annotations declare readOnlyHint=false, consistent with a form-filling mutation. The description adds useful context (faster, more reliable, reduces turn count) and the batch semantics, but discloses nothing about failure behavior, atomicity, or what happens when a uid is invalid. Adds some value but not rich behavioral context.

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?

Front-loaded with the core action and the preference rule, followed by a justified example. Slightly promotional ('significantly faster, more reliable') but each sentence still earns its place by steering tool selection.

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?

No output schema exists, so the description needn't explain return values, and the annotations are minimal enough that the description covers the mutation nature and batching benefit. It is complete enough to invoke correctly, though it omits error/atomicity behavior for a multi-element write.

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%, and the schema already documents pageId, elements, uid, value, and includeSnapshot, including the 'true'/'false' conventions for checkboxes and radios. The description adds the example semantics but no new parameter meaning beyond the schema, so baseline 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?

The description states a specific verb (Fill out) and resource (multiple form elements, enumerating inputs, selects, checkboxes, radios) in one call. It clearly distinguishes itself from the sibling tools 'fill' and 'click' by emphasizing the batch nature.

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?

Explicitly states 'ALWAYS prefer this tool over multiple individual fill or click calls when interacting with forms,' giving a direct when-to-use rule and naming the alternatives. A concrete example (username, password, Remember Me) further grounds the guidance.

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