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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the bar is lower, but the description adds no behavioral context whatsoever. It says nothing about the presence of a callback_id implying async execution, generation latency, rate limits, or whether reference images alter output — all relevant for a generative write tool.

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?

It is short, but this is under-specification rather than conciseness — a four-character fragment carries no actionable content. There is nothing to be front-loaded because nothing is said.

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?

For a 9-parameter generative tool with an async callback parameter, no output schema, and zero explanation of input meaning or return behavior, the description is completely inadequate. An agent cannot determine what event_info should contain, what method values are valid, or what the tool returns.

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?

The schema documents all 9 parameters (100% coverage), so the baseline of 3 applies even though the description adds no parameter detail. That said, the schema labels are themselves terse restatements ('海报生成方法' for method), so the description does not compensate with any semantics of its own.

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 is a bare noun phrase ('活动海报图') that essentially restates the tool name image_poster. It conveys the resource ('poster') but no verb or action, and it offers nothing to distinguish this from siblings like image_create, image_ecommerce, or image_enhance.

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?

There is no indication of when to use this tool versus the many other image_* siblings, nor any prerequisites or exclusions. The agent is given no routing information at all, leaving selection entirely to inference from the name.

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