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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds useful scope (which resources' limits/usage are reported) but says nothing about response shape, refresh/lag of usage data, or permissions — moderate added value only.

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 return content, then the practical use case, then the API endpoint. The long resource enumeration earns its place because there is no output schema to convey the coverage.

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 and no parameters, the description must carry the return-value burden; it lists the covered resources and states that both limits and usage are returned. It stops short of describing structure/units, which an agent might still want, but is largely complete for a simple read 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 to disambiguate; baseline 4 applies. The description correctly implies no input is required.

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 states a specific resource (the account's quota: limits and current usage) and enumerates the resource categories it covers, so an agent can distinguish it from the many list_* siblings. The verb 'get' is carried by the name/title and the enumerated scope makes the output unambiguous.

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 phrase "Answers 'can I launch another one?'" gives a concrete decision context — check capacity before provisioning. It doesn't name alternatives or exclusions (e.g., use list_charges for billing), so it's clear context without explicit routing.

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