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

Annotations already declare destructiveHint=true, readOnlyHint=false, and idempotentHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: it is free, and the call is refused (not silently allowed) when stored files wouldn't fit, with an explicit remediation path. It doesn't state whether removing a block causes any data loss or billing proration, which matters for a destructive call.

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 short, front-loaded sentences with no filler: action first, then the failure condition, then the cost. Every sentence carries distinct information.

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 parameters, no output schema, and annotations covering destructiveness, the definition supplies nearly everything needed: effect, precondition, remedy, and price. Minor gap: no statement about whether files are affected or what the response confirms.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly signals the call is parameterless by describing a fixed-size block removal.

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: stop renting one 10 GB block, which is a precise, concrete action. It implicitly distinguishes itself from files_add_storage by being the inverse operation, but never names that sibling, so differentiation is left to inference.

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 precondition (refused while files would no longer fit) and the remedy (delete files first), which tells the agent exactly when this call will fail and what to do instead. It stops short of naming the add/capacity siblings or describing when the agent should proactively suggest it.

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