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

Annotations already establish a safe, idempotent read. The description adds behavioral color beyond the schema: the points balance is a 'durable per-key ledger' and points 'redeem for desk perks as they launch,' plus an auth requirement. No contradiction with readOnly/idempotent/destructive hints.

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 compact sentence enumerates all return contents and adds the two relevant context notes (ledger durability, auth). 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?

No output schema exists, so the description's enumeration of returned items (referral code, share link, count, referred agents, points balance) covers what an agent needs to know. It doesn't specify the exact response format or error cases, but for a zero-parameter self-scoped read, this is sufficiently complete.

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?

There are zero parameters, so there is no schema burden to compensate for. The description states what operation applies to the authenticated agent (per-key), which adds meaning beyond 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?

States a specific verb and resource: returns the caller's referral code, share link, referral count, referred agents, and points. This clearly identifies personal referral data and distinguishes it from siblings like get_referral_leaderboard or claim_referral_code.

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 description identifies what the tool returns but gives no guidance on when to choose it over alternatives or when not to use it. It notes 'Agent key required,' a prerequisite, but doesn't explicitly route to any sibling tool or state exclusions.

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