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

Annotations already declare readOnlyHint=false and openWorldHint=true, covering the mutation and side-effect aspects. The description adds the 'optionally submit' behavior, which is useful. It does not go deeper into overwriting or navigation effects, but with annotations present, this is adequate.

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, appropriately sized sentence that is front-loaded with the core action. No filler or unnecessary repetition.

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 simple tool with two parameters, the description covers the essential action and the optional submit. Annotations provide safety context, and no output schema is needed. The description is complete enough for an agent to select and invoke the tool correctly for a bulk fill operation.

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 0%, but the description provides the {selector, value} structure for the fields array, adding meaning beyond the bare schema. It does not specify the types or semantics of selector and value, nor the exact behavior of the submit parameter beyond the schema's boolean default.

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' with the resource 'multiple form fields', clearly distinguishing it from sibling tools like type_text (single field) and click. It also notes the optional submit action, which conveys the full scope of the tool.

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?

The description clearly implies this tool is for filling multiple form fields at once, with an optional submit. It provides context, though it does not explicitly exclude single-field use or name alternatives. The sibling list provides a natural contrast, but the description itself does not mention when not to use it.

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