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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered without prose. The description adds genuinely new behavioral context: the call is free ("Costs 0 credits") and it surfaces credit breakdown (plan credits vs. non-expiring packs) plus rate limit windows, which matters for planning subsequent calls.

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?

Two short sentences, front-loaded with the resource list and closed by the cost fact — the most decision-relevant detail. No filler, no restating of the title, and every element earns its place.

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?

For a zero-parameter, read-only tool with an output schema and full annotation coverage, the description covers what is read and its cost. The only shortfall is that it does not say when in a workflow an agent should reach for it, though the low complexity limits how much that matters.

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 the baseline is 4; there is nothing for the description to disambiguate. The enumerated field list is about outputs rather than inputs, so it neither helps nor hurts parameter understanding.

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?

Uses a specific verb ("Read") with an enumerated resource set: plan, key charge_order, credits (monthly vs. never-expiring packs), daily credits, rate limit windows, and active jobs/tracks. This makes it unmistakably the account-introspection tool, easily separated from siblings that deal with markets, bookmakers, codes, or slips.

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: an agent can infer it should call this to check quota/limits or inspect active jobs, and "Costs 0 credits" nudges toward free pre-flight checks. There is no explicit when-to-use, when-not-to-use, or pointer to which sibling to use for job/track management instead.

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