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

Beyond the annotations (readOnly=false, idempotent=false, destructive=false), the description discloses that the extension is billed as storage to the owner and capped at 720 hours from now. These are meaningful operational facts an agent needs; reversibility and stacking behavior remain unstated.

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 sentences, zero waste, with the core action front-loaded. Everything stated earns its place except the mild restatement that owner_ticket is required, which is trivial.

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 two-param mutation tool with annotations covering the safety profile and no output schema, the definition covers billing, prerequisites, and the cap. Edge cases such as failure behavior or whether extensions stack are omitted but not critical.

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 a real constraint not in the schema: the 720-hour maximum on add_hours. It also reinforces that owner_ticket is mandatory, adding modest value over the schema text.

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?

"Push an item's expiry later" gives a specific verb and resource, and the billing clause distinguishes it from sibling storage tools. It does not explicitly name an alternative sibling, but the core action is unambiguous.

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?

The description implies you use it to extend storage and states the owner_ticket is required, but gives no explicit when/when-not guidance or named alternatives among the many storage siblings. Usage is inferable but not spelled out.

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