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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered and the description does not contradict it. Beyond that, the description usefully discloses the authentication requirement (a partner key is needed to scope results to the caller's own account) and lists the fields returned. It says nothing about rate limits, pagination, empty-state behavior, or how the lookback window affects results.

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?

One dense, front-loaded sentence plus a short prerequisite line; the earnings split and tier definitions come before the secondary metrics, which is the right ordering. The long comma-separated enumeration is information-dense rather than padded, though it could be split for scanability.

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?

With no output schema, the description does the necessary work of enumerating what comes back (earnings buckets, tiers, payout eligibility, referred partners, buyers, daily hits, accruals), which is exactly what an agent needs to decide whether the response answers its question. The main remaining hole is the undocumented days window, which matters for a stats tool with a 90-day cap.

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%, so the description carries the full burden for two parameters. It mentions partnerKey only as "Needs your partner key" without format or where to obtain it, and the days parameter (1-90) is never referenced at all — the agent cannot tell from the description that it controls the reporting window for hits/accruals.

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 opens with a specific verb+resource ("Your partner stats") and then enumerates exactly what is reported: pending/available/paid earnings split by tier 1 (20%) and tier 2 (5%), payout eligibility, referred partners, attributed buyers, ref hits per day, and recent accruals. That level of detail makes it unmistakable against siblings like partner_check_ref, partner_pitch_kit, partner_program and partner_signup, which cover tracking, marketing, program info and registration rather than earnings.

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: the tool is for a partner inspecting their own earnings, and the closing sentence states the prerequisite "Needs your partner key." There is no explicit when-to-use vs when-not guidance and no pointer to sibling tools (e.g. partner_check_ref for tracking a referral), so the agent must infer routing from the content list.

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