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

The description says the tool extends a server and charges money ('each month is billed at the plan's monthly price', 'Pay in stablecoins with x402 or MPP'), which is a state-changing, billable operation, while annotations declare readOnlyHint=true and idempotentHint=false. This is a direct inconsistency between the stated behavior and the safety annotation.

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?

Six short sentences, front-loaded with the action and scope before moving to payment and retention details; each sentence carries information. Slightly verbose, and 'Use the renew route that matches the server's plan' is vague filler rather than a crisp instruction.

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-parameter renewal tool with no output schema, the description covers payment rail, data/IP retention, and the consequence of not renewing, which is a lot of useful context. It omits what happens after expiry (can a lapsed server still be renewed) and any response/payment-confirmation behavior.

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 both parameters are already documented in the schema, including the billing note that the description repeats. The description adds only the provenance detail that the id comes 'from the order', which is marginal added meaning.

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 (extend/renew) plus the exact resource (a medium server) and the scope (one to six months), which cleanly separates it from vps-medium (ordering) and vps-small-renew (the other plan's route). The closing line 'Use the renew route that matches the server's plan' explicitly routes away from the sibling plan.

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 concrete invocation guidance ('Send the server id from the order and the number of months') and consequence context ('A server that is not renewed stops at its expiry date'). It never states an explicit when-not or a named alternative, so it stops short of full routing guidance.

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