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

Annotations already cover safety (readOnlyHint=false, destructiveHint=false, idempotentHint=true), but the description adds real value beyond them: the operation is asynchronous and returns an event_id, and 'the cache refills on demand' explains why the flush is non-destructive and effectively idempotent. It stops short of saying how to retrieve the returned event, which the sibling spinupwp_get_event would handle.

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 tight sentences: operation class and scope first, then the behavioral consequence, then the async return, closing with the endpoint. No filler and the most important constraint (write + precondition) is front-loaded.

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?

There is no output schema, and the description compensates by naming the return value (event_id). The precondition and non-destructiveness are stated, so an agent can invoke it correctly. The only gap is not pointing at spinupwp_get_event for polling the async result, which would have made it self-sufficient end to end.

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?

With a single parameter at 100% schema description coverage, the schema fully documents site_id ('SpinupWP site id.'), so the description carries no additional parameter burden. It adds nothing about site_id format or sourcing, which is the expected baseline at this coverage level.

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 ('flush') and precise resource ('Redis object cache of one site'), and the 'WRITE:' prefix flags the operation class immediately. The phrase 'object cache' also implicitly separates it from the sibling spinupwp_purge_page_cache, so an agent can distinguish the two without opening a schema.

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 one useful precondition ('the site must have object caching'), which is genuine when-to-use context. However, it never contrasts with the adjacent spinupwp_purge_page_cache or explains when a purge is warranted versus not, so the alternative-selection guidance is only implied.

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