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

The annotation already sets readOnlyHint=true, so the description adds value by noting the default placeholder behavior for image data and that a layout with placeholders is rejected on update. This goes beyond annotations but doesn't detail other behavioral traits like auth requirements or rate limits, which are not covered by annotations either.

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 sentences, front-loading the primary action and then clarifying a key behavioral option. The language is efficient, but the sentence about placeholders could be slightly tighter (e.g., 'By default, inline image data is replaced with placeholders for readability').

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 moderate complexity (2 params, no nested objects, no output schema to describe), the description effectively covers the core functionality and a critical behavioral nuance. It does not explain the return structure in detail, but the description implies it includes layout JSON and translation overrides, which is sufficient for this context.

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 the baseline is 3. The description reiterates the purpose of 'include_image_data' (default false, placeholder vs raw data), which adds some context but mostly mirrors the schema's description. No new semantics are added for 'set_id'.

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 uses specific verbs and nouns: 'Fetch a screenshot set in full', details what it returns ('layout JSON plus per-screen translation overrides keyed by locale'), and distinguishes itself from siblings like 'sonar_get_app' or 'sonar_update_screenshot_set' by specifying the read-only, comprehensive nature of the output.

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 provides clear context on when to use the tool, such as fetching full data for a screenshot set. However, it does not explicitly mention when not to use it or provide alternatives among the many screenshot-related siblings like 'sonar_list_screenshot_sets' or 'sonar_export_screenshots', which could guide selection more precisely.

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