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

With readOnlyHint already declaring the safe read nature, the description adds meaningful context: it reads the stored file inline and falls back to a signed URL past 4MB. This goes beyond the annotation by clarifying the delivery mechanism and response format.

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?

A single sentence packs the core purpose, the image nature, and the storage/fallback behavior without redundancy. The structure front-loads the key purpose and uses a dashed aside for technical detail, making it easy to scan.

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 simple read-only image retrieval, the description plus readOnlyHint covers the return mode and storage behavior. However, it lacks parameter usage guidance and does not fully compensate for the undocumented project_id or clarify how to select the correct screen when multiple parameters are available.

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 67%, with id and name described but project_id not. The tool description does not explain parameter relationships or selection precedence, leaving the undocumented project_id without compensation. The description adds no meaning beyond the schema's parameter hints.

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 indicates the tool retrieves a screen's reference image as a viewable image, with 'reads the stored file inline' providing a specific verb. It distinguishes itself from sibling get_screen by emphasizing the actual image output, though it lacks an explicit imperative verb.

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 phrase 'as an actual IMAGE you can see' implies when this tool should be used, but it does not explicitly state when to use it versus alternatives like get_screen or list_screens. No exclusions or alternative recommendations are provided, so usage guidance is only implied.

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