Read candidate thumbnails for host display

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value by clarifying what it does NOT do—confirm exact previews or create materialization receipts—which sets expectations beyond the structured annotation values.

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?

Three sentences, each earning its place: result shape, usage instruction, and explicit exclusions. No filler or 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?

The description is complete enough for a simple two-parameter, read-only tool with no output schema. It states input constraints, output type ('standard MCP images'), and limitations. It could specify how resultSetId is obtained or the relationship to a prior search, but for this scope the gaps are minor.

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 0%, so the description must compensate for parameter meaning. It only weakly connects to the parameters with 'current-result thumbnails' and 'exact candidate labels'; 'up to 12' repeats the schema's maxItems. It does not explain what resultSetId represents or how candidateIds relates to a result set.

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: 'Get up to 12 current-result thumbnails as standard MCP images with exact candidate labels.' The negative clause 'Does not confirm exact previews or create materialization receipts' distinguishes it from preview/confirmation tools, so agents can tell it apart from siblings like preview_exact.

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?

Gives concrete usage context via 'Display a page for user selection; do not iterate the entire result set,' and an explicit limitation: does not confirm exact previews or create materialization receipts. It does not name an alternative sibling tool, so it stops short of full 5.

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