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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the return is native MCP image content, which matters for downstream handling. It does not mention failure modes such as missing files or unsupported formats.

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?

Two sentences, zero filler, with the usage condition front-loaded before the alternative-tool warning. Every clause carries information.

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?

An output schema exists, so return values need not be detailed, and the description still adds the key fact that the output is image content. Combined with full parameter documentation and safety annotations, an agent has what it needs; only edge-case behavior (large images, errors) is unstated.

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 100% and both parameters (path, device) are fully documented in the schema, including where the device id comes from. The description adds no format, path-resolution, or device-binding detail beyond what the schema states, so the baseline 3 is appropriate.

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?

States a specific verb (read/inspect/show) and resource (image on a paired computer) and gives concrete examples (screenshot, photo, diagram). It explicitly distinguishes itself from read_binary, so an agent can select it without opening the schema.

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?

Provides a clear triggering condition ('when the user wants to inspect or show an image') and an explicit negative routing rule ('do not use read_binary merely to display an image'). It does not address other plausible alternatives in this large sibling set (take_screenshot, screenshot_region, read_document), leaving some selection ambiguity.

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