fill_form

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

With no annotations provided, the description carries the full burden of disclosing behavior. It states the tool fills and submits a form, but it does not disclose that it saves session state by default (as seen in save_session parameter), or any side effects of submission. The phrase 'Supports login automation' hints at session handling but does not explain the actual behavior or consequences.

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 two short sentences with no unnecessary words. It front-loads the core action and then adds a key use case, making it effectively scannable for an AI agent.

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 is adequate for a simple understanding but lacks important context. It does not explain when to use this over browser_* siblings, does not mention session management behavior, and does not clarify what happens after submission. The existing output schema covers return values, but the description still feels incomplete for a tool with 6 parameters and many related browser tools.

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 high (5/6 = 83%), so the schema already documents most parameters. The description adds no parameter-specific meaning beyond implying that 'fields' are the values to fill. It does not compensate for the undocumented timeout_profile parameter, but the strong schema coverage keeps this at baseline.

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 'Fill and submit a web form' clearly identifies the tool's specific action and resource, and 'Supports login automation' adds a common use case. It implicitly distinguishes itself from sibling tools like browser_type (single field typing) and browser_click (single click) by combining fill and submit into one operation, though it does not explicitly name alternatives.

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 implies a usage context ('Supports login automation'), suggesting it is appropriate for automating form submissions, especially login flows. However, it provides no explicit guidance on when to use this tool vs alternatives, no exclusions, and no mention of scenarios like simple single-field interactions where browser_type or browser_click would be more suitable.

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