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

Annotations already declare readOnly=false, idempotent=true, destructive=false and openWorld=true, so the safety profile is covered. The description's genuine addition is the plan-gating fact ('Part of Premium'), which an agent needs. It does not disclose what happens when the flag is set to off (e.g., reverting to a default UPI ID), leaving a behavioral gap for a mutation tool.

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 tight sentences with no filler; the functional effect is front-loaded and the plan-gating note follows. The phrasing 'take turns being quoted' is slightly indirect but still earns its place.

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?

Complexity is low (one boolean, output schema present, rich annotations), so little detail is required. Still, the off-state behavior and any prerequisite of having multiple active UPI IDs are unstated, leaving an agent to guess at the practical effect of disabling rotation.

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 0% for the single 'enabled' boolean, so the description carries the burden and largely does: 'When on, active UPI IDs take turns' explains what true means in domain terms. It does not explicitly define the off-state, but it substantially compensates for the empty schema.

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?

The description conveys the feature's effect ('active UPI IDs take turns being quoted') but never states the tool's own action — that it sets/toggles rotation on or off. An agent can infer it from the name and the 'when on' phrasing, but no explicit verb+resource is given, and it does not distinguish itself from siblings like set_default_upi_id or update_upi_id.

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?

'Part of Premium' is a real usage prerequisite. However, there is no guidance on when to enable vs. disable rotation, no mention of prerequisites such as needing multiple active UPI IDs, and no routing to alternatives like add_upi_id or set_default_upi_id.

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