fill_form_field

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

No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing: not what happens if the selector matches nothing, whether existing field content is overwritten or appended, whether input/change events are dispatched, or whether a live browser session/page must already be open. For a page-mutating automation tool this leaves significant gaps.

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?

Two short sentences, zero filler, with the core action front-loaded and the prerequisite trailing. Every clause earns its place.

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?

With no annotations and no output schema, the description is the only source of behavioral context, and it omits failure behavior, event semantics, and session prerequisites. It is adequate for a two-parameter tool whose schema is complete, but thin for a browser-mutating 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 coverage is 100% so the baseline is 3, but the description adds real meaning by specifying that the selector should originate from extract_form_fields, which is workflow information the schema's 'CSS selector for the field' does not convey. The value parameter remains fully schema-documented only.

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?

States a specific verb (Fill) and resource (a single text input or textarea field), and scopes it to exactly one field on the current page. That scope distinguishes it from broader form tools, though it never names the closest sibling (select_form_option) for non-text form controls.

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?

Gives an explicit prerequisite/source for its input: 'Use the selector from extract_form_fields,' which tells the agent it must run extraction first. It stops short of stating when-not to use it (e.g., dropdowns/checkboxes belong to select_form_option), so no explicit alternative routing.

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