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

Annotations already cover read-only/idempotent/non-destructive, and the description adds genuinely new context beyond them: the call 'Draws no credit', so agents know it is free to invoke defensively. It does not disclose auth requirements or whether entitlement data can be stale, which keeps it below 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?

A single tight sentence that front-loads the payload (account entitlements) and ends with the cost-free assurance. The 'steps to relay to your user...' clause is a bit recursive and slightly obscures what the tool returns versus what the agent should say.

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 parameters and no output schema, the description must convey the return contents, and it does list them (readable scope, cost, remaining quota, upgrade path). It stops short of describing the response shape or how quota periods are defined, a minor gap for a simple info tool.

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 zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly spends no words on arguments.

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?

Names a specific resource (the connected account's access/plan state) and enumerates its contents: readable scope, per-call cost, remaining monthly quota, and upgrade steps. It is clearly distinguishable from every sibling, which are all market-data lookups. Slightly muddled phrasing ('what a call costs and what is left this month') keeps it just short of a crisp verb+resource statement.

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 mention of 'the steps to relay to your user when a result needs more than the account allows' hints at calling this after hitting a limit, but there is no explicit 'call this before/after X' or exclusion guidance. An agent must infer the trigger condition.

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