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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds a little scope context by stating the other UPI IDs remain on the account, reinforcing non-destructiveness, but says nothing about permissions, failure behavior, or what happens to the previously-default ID.

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, front-loaded with the action, and the second sentence adds non-destructive scope rather than filler. Nothing is wasted.

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?

An output schema exists, so return values need not be described, and annotations cover the safety profile. However, for a single-parameter mutation the description leaves the parameter's meaning and the source of the ID unexplained, which is a real gap for correct invocation.

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% and the description never references the single 'id' parameter — it neither names it nor explains that it is the numeric identifier of the UPI ID to promote, nor how to obtain it (e.g., from list_upi_ids). With one undocumented parameter, the description fails to compensate.

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 gives a concrete verb and resource: make one UPI ID the one supporters are shown first. This is distinguishable from 'update_upi_id' (editing details) and 'set_upi_rotation' (rotating among IDs), though it never explicitly names those siblings to sharpen the boundary.

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?

Usage is only implied — an agent can infer you call this when you want a different UPI ID shown first. There is no explicit when-to-use/when-not guidance and no mention of the closest alternatives (update_upi_id, set_upi_rotation), which an agent must disambiguate itself.

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