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

Annotations already establish the safe read-only, closed-world profile, and the description adds real substance beyond them: credits are consumed by publishing (one) and by extra phone-guest batches (one more), generations_remaining never resets over time, and each purchased credit yields 5 generations. It stops short of stating auth/permission needs or any freshness/caching behavior, which keeps it below a 5.

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 user questions, then the two field definitions, then credit rules, then sibling routing. Every sentence carries functional information (cost model, non-resetting counter, 5-generations-per-credit conversion) 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?

With zero parameters, a present output schema, and annotations covering the safety profile, the description supplies everything else an agent needs: when to call it, how to interpret the two numeric fields, and which sibling to use for the adjacent credit questions. Nothing material is missing 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?

The tool takes no parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The prose describes the account fields returned rather than call inputs, which is appropriate here.

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?

It names a specific resource (the connected Lemonvite account) and enumerates exactly what the caller learns: which account is connected, credits, and generations_remaining. The two returned quantities are defined in domain terms, so an agent can tell this apart from siblings like lemonvite_get_invitation without opening any schema.

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 opening clause states the user intents that should trigger this call, and the closing clauses route the agent elsewhere when appropriate: lemonvite_start_checkout for adding credits, lemonvite_get_invitation (required_credits) for per-invitation cost. When-not-to-use is handled by explicit alternative naming rather than inference.

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