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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, and the description's trailing 'Read-only' merely restates that. It adds some value by clarifying that raw image pixels are returned rather than metadata, but nothing about size, format constraints, or errors.

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 short sentences with the core behavior front-loaded and no filler; the read-only note is the only redundant element, and it costs almost nothing.

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?

This is a simple two-parameter read tool with full schema coverage and an output schema, so return-value explanation is unnecessary. The description covers what an agent needs to call it correctly; only the fetch-workflow context is thin.

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% and the path parameter already carries an example plus its source, so the schema does the heavy lifting. The description only confirms the path is project-relative, adding marginal meaning beyond the schema.

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 and resource ('Returns the image pixels of a project screenshot') and scopes the input as a project-relative path, which clearly separates it from listing tools like list_screenshots. It stops short of naming a sibling explicitly, so it is clear but not maximally differentiating.

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?

Usage is only implied: the schema's path description says the value comes from list_screenshots or a layout's screenshot.path field, which hints at the retrieval workflow. The description itself gives no when-to-use or when-not-to-use guidance relative to list_screenshots, preview_screenshots, or get_layout.

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