simscale_fill

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

The description discloses a key behavioral trait: password fields are blocked and require manual entry. This goes beyond the annotations (which only indicate mutation and non-idempotency) by revealing a specific limitation. It does not contradict annotations, and it adds context about how the tool behaves for a certain field type.

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. The first sentence states the core function and the second adds a critical limitation. There is no filler or redundant information. It is very concise and front-loaded.

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 conveys the main action and a limitation, but it omits details about error behavior (e.g., what happens when a field is not unique or not visible), return values (there is no output schema), and how the value parameter should be used. Given the moderate complexity (nested target object) and lack of output schema, the description is adequate but has clear gaps.

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 tool description adds no explanation of the parameters. The schema provides a description for 'target' ('A stable, visible UI target...') but 'value' is only typed as a string with no guidance. The description could compensate for this gap but doesn't, leaving the agent to infer what 'value' means and how it might be formatted.

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 action: 'Fill one unique visible SimScale field.' It specifies a specific verb (fill), a resource (SimScale field), and adds constraints (one, unique, visible). This distinguishes it from sibling tools like simscale_click or simscale_press, and the note about password fields adds clarity about what it does (and doesn't) handle.

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 gives an explicit exclusion: 'Password fields are blocked and must be completed manually in Edge.' This tells the agent when not to use this tool. However, it does not explicitly mention when to use it or compare it to alternatives (such as simscale_press for keyboard input), making it clear but not fully comprehensive.

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