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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine semantic context beyond that: publishing cadence 'warns and never refuses,' Handler slot allocation is the stricter rhythm with no monthly ceiling, and tier is a legacy class derived from subscription state. It does not mention auth requirements or cost, but for a read-only tool that is minor.

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?

Purpose is front-loaded, but the bulk of the text is a dense enumeration of returned fields, which an output schema already documents. The sentence separating the four limit kinds is long and clause-heavy, and the plan/tier explanation reads like internal documentation rather than call guidance. Some of it earns its place by disambiguating which limit applies, but it is over-long for a zero-parameter read.

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 an output schema present and no input parameters, the description supplies the interpretive layer the schema cannot: which limit governs what, when warnings fire versus refusals, and how plan/tier are derived. The remaining gap is routing — it does not tell the agent when this is preferable to get_plans or capabilities.

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; the baseline for a no-param tool applies. The description correctly spends its words on output semantics instead of inventing parameter context.

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 opening sentence gives a specific verb and resource: 'Reads this account's limits and live usage.' It is clear what the tool returns. It does not explicitly distinguish itself from near-siblings like get_plans or capabilities, which likely overlap on plan/limit information, leaving the agent to infer the boundary.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative. The description explains what the returned fields mean, but never says e.g. 'call get_plans for the catalogue of available plans' or 'call capabilities for feature flags.' Usage is only implied by the resource being read.

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