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

Annotations already declare readOnlyHint/destructiveHint/openWorldHint. The description adds meaningful context beyond them: it requires auth and the read:account scope, and it enumerates what the response contains (counts, spend, kickback in cents, per-referral rows). Slight redundancy on 'read-only' but the auth/scope disclosure is real value.

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?

Front-loaded with the triggering condition, then returns, then behavioral constraints. Three tight clauses with no filler.

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?

Purpose, trigger conditions, auth/scope requirements, and return shape are all covered, and an output schema plus rich annotations handle the rest. Nothing an agent needs to call it correctly is missing.

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?

All four date-window parameters are documented in the schema at 100% coverage, so the baseline of 3 applies. The description adds no extra meaning about the order_* vs referral_* semantic distinction beyond what the schema offers.

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 and resource ('their XP marketplace referral kickback totals and rows') with concrete example queries, making it easy to distinguish from siblings like get_my_orders or get_my_wallet. The scope (XP marketplace referrals) is precise.

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 'Use when an authenticated user wants...' clause plus two example queries gives clear context for when to invoke it. It does not name explicit alternatives or exclusions, so a 4 rather than 5.

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