read_screen

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

With no annotations, the description must cover behavior. It states that a screenshot and UI structure are captured, and optionally saves a PNG. However, it does not disclose potential side effects (e.g., whether it modifies the UI) or prerequisites (e.g., requires a running Pharo instance). This is adequate but not exhaustive.

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 well-structured with a purpose statement, parameter breakdown, and return fields. It is concise but could be slightly more streamlined. No unnecessary repetition.

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?

Given the tool's simplicity (2 parameters, output schema present), the description covers inputs and outputs adequately. It lacks error handling or edge cases, but is sufficient for a debugging tool.

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 baseline is 3. The description adds value by mapping target_type values to specific UI elements (morphs, windows, visualizations) and clarifying the screenshot return behavior, exceeding the schema details.

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 identifies the tool as a 'comprehensive UI screen reader' for debugging Pharo interfaces, with specific target types (World morphs, Spec presenters, Roassal visualizations). This distinguishes it from sibling tools like eval or list_classes, which serve different purposes.

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 usage for UI debugging and lists three target types, giving clear context. However, it does not explicitly state when not to use this tool or provide alternatives, though no direct sibling overlaps exist.

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