fill_form

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

With no annotations, the description takes full responsibility for behavioral disclosure. It explains that fields are cleared before typing (avoiding concatenation) and that the tool reports which selectors succeeded and which were missing, enabling detection of partial fills. This goes beyond the schema.

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 three sentences, each serving a distinct purpose: purpose, reporting behavior, and clearing behavior. It is front-loaded and concise, with no wasted words.

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?

The description covers purpose, input format, key behaviors, and return semantics. It lacks mention of prerequisites (e.g., page must be loaded) or error handling, but for a simple tool with one parameter and output schema, it is largely complete.

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?

The input schema provides no description for the 'form_data' parameter (0% coverage). The description fully compensates by explaining that it is a JSON string mapping CSS selectors to values, with an example. This is essential for correct invocation.

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 clearly states the tool fills multiple form fields with a JSON mapping of selectors to values. It distinguishes from siblings like 'type_text' by indicating it handles multiple fields at once, but does not explicitly contrast with other form-related tools.

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 on when to use this tool versus alternatives such as 'type_text' or 'clear_input'. The description implies usage for filling multiple fields, but does not set conditions or exclusions.

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