fill_form

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

Annotations already mark the tool as non-readOnly and destructive, so the bar is lower. The description adds key behavioral details: 'Fields are executed sequentially (order matters for dynamic forms)' and 'Stops on first error or navigation,' plus a security warning about untrusted element names. This exceeds the annotation coverage and provides important operational 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?

The description is structured in short, purposeful sections: purpose, benefit, execution semantics, security warning, and parameter summary. It front-loads the main verb and resource, and despite the detail, every sentence adds value without redundancy.

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 batch form-filling tool with a single array parameter and an output schema, the description covers purpose, usage context, execution order, error handling, and a security caveat. The only missing piece is an explicit note about return behavior, but the presence of an output schema makes that unnecessary.

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%, so the description must compensate. It does so by explaining each field's components (ref, action, value), stating that value is required for type/select, and providing a concrete JSON example. This adds meaning beyond the minimal schema definitions.

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 opens with a specific action and resource: 'Fill multiple form fields in a single batch call.' It clearly distinguishes from siblings by emphasizing the batch nature and gives example use cases (login, checkout, search forms), which differentiates it from single-action tools like execute_action.

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?

It explains when to use the tool: for forms where you want to reduce round-trips, and notes that fields execute sequentially and order matters for dynamic forms. It doesn't explicitly name an alternative or give when-not-to-use, but the context implies using this for multi-field batch operations rather than single-action tools.

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