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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds genuinely useful context beyond them: the call is free, the reset time is UTC, and it is the diagnostic to run after 401/403/429. It does not describe caching, staleness, or whether quota figures update in real time.

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?

One sentence states the payload, a two-word sentence states the cost, and one sentence states the trigger — all front-loaded with zero filler. Every clause 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?

With an output schema present, the description does not need to enumerate return fields, yet it summarizes them anyway, which helps an agent decide to call it. For a zero-param read tool this is close to complete; only edge behavior (e.g., what tier/quota values look like when unauthenticated) is unaddressed.

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 no parameter semantics to explain; baseline 4 applies. The description correctly adds no spurious parameter guidance.

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 names the exact resource and its contents: caller's tier, daily quota used/remaining, UTC reset time, and capability flags (verified email, scanner, paper trading). That is far more specific than the bare name 'get_account'. It does not explicitly contrast itself with near-siblings like get_meta or get_paper_account, so it stops short of a 5.

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?

It gives a concrete trigger: 'Use when a call was refused with 401/403/429,' which tells the agent exactly when to reach for this tool during error recovery. It also signals 'Free,' implying the call does not consume quota. There is no explicit when-not-to-use or named alternative, which keeps it at 4.

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