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

Annotations already declare destructiveHint=true and openWorldHint=true; the description adds real value on top by stating the required Cache Purge token permission, which is the main failure mode for this call. It does not mention that a purge is irreversible/instantly affects live traffic or any rate limits, which would be the remaining useful disclosure.

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?

Two short sentences with no filler; the scope and the four modes come first and the permission requirement follows as the supporting constraint.

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 8 parameters but 100% schema coverage, an output schema, and full annotations, the description needs only to frame the operation and its prerequisite, which it does. A note that purges are immediate and irreversible would close the last gap.

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 100%, so every parameter including the account/context routing fields is already documented; the description only loosely maps its mode list onto files/tags/hosts/prefixes. Baseline 3 is appropriate since the schema does the heavy lifting.

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 (purge) and resource (cached assets for a zone) and enumerates the four purge modes (urls, cache-tags, hosts, prefixes), which cleanly separates it from read-only siblings like cf_cache_probe, cf_cache_analytics, and cf_cache_purge_history.

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 a clear operational context ('purge cached assets for a zone') and a prerequisite (API token with Cache Purge permission). It stops short of naming when NOT to use it or pointing at cf_cache_probe for verification or cf_cache_purge_history for auditing, so it is clear context without explicit alternatives.

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