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

Beyond the readOnlyHint annotation, it discloses meaningful behavior: finished items render instantly while rendering ones fill in, and display=false returns state + URLs as data without rendering for chaining. These are non-obvious operational traits the annotations do not cover.

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?

Front-loaded with the core purpose, then usage rules, then parameter guidance. Dense and largely waste-free, though the trigger-phrase list and arrow shorthand make it longer than strictly necessary for an agent reader.

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?

With no output schema, the description compensates by explaining what display=false returns (states + URLs). Combined with routing rules and item constraints, an agent has everything needed to select and invoke it correctly.

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, but the description adds real context: items accepts 2–24 mixed placeholder_ids and var2 links across images/videos/tracks/3D, and it clarifies the display flag's purpose for chaining rather than merely restating the schema. The empty-items prohibition reinforces the minItems constraint.

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+resource with scope: 'Show 2+ finished results in one gallery (browse / sort / group / filter)'. It explicitly routes the single-result case to var2_get_<modality>_result, so an agent can distinguish it from the entire var2_get_*_result family without opening schemas.

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 concrete trigger phrases, an explicit boundary rule ('2+ existing var2 links or ids = THIS tool, not an upload'), a negative constraint ('Never call with empty items'), and names the correct alternatives for single results, model listing, and voice listing.

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