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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds ordering ("newest first") and the taxonomy of change events, which is genuine added context, but says nothing about pagination, default result size, or entitlement/auth requirements for reading billing history.

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?

A single front-loaded sentence with no filler; the ordering fact is placed early where it matters. It is tight, though a clause on filtering would have earned its space more than the colloquial "right-size moves" framing.

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 no explanation, and the safety profile is annotation-covered. But for a 6-parameter, filter-rich billing-history tool at 33% schema coverage, the description leaves the entire filtering surface and business scoping unaddressed — a moderate completeness gap rather than a fatal one.

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 only 33% across 6 parameters, so the description must compensate and does not. Time window (from/to), limit with its 50/100 bounds, and the source values are left entirely to the schema, and the enumerated change types in the description don't cleanly map onto the change_type enum values (plan_change, created, canceled, reactivated, rightsize).

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+resource ("List the business plan and price changes") and adds scope detail ("newest first: upgrades, downgrades, add-ons and automatic right-size moves"). An agent knows exactly what the tool returns, though it doesn't distinguish itself from the sibling get_change_history or list_rightsize_recommendations.

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 by the resource domain — there's no statement of when to reach for this versus get_change_history or list_rightsize_recommendations. No prerequisites, no exclusions, no context about token scoping despite business_id being optional in some cases.

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