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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds no behavioral context beyond that — no auth/permission requirements and no note that data is account-scoped to the caller's own credentials — and its second sentence describes return shape rather than behavior.

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 sentences, front-loaded with the purpose and followed by concrete field names. Slight waste: the parenthetical field list (monthly_requests, search_results, history_days, etc.) largely restates what the output schema already declares, so it earns less than its length suggests.

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?

A zero-parameter read tool with an output schema and full annotation coverage needs only a clear statement of what it returns and when it's relevant; the description supplies both, including the conditional scheduled_tier/scheduled_change_at fields. Nothing needed to invoke it correctly is missing.

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 and the baseline of 4 applies. The description correctly implies a parameterless call by never referencing any inputs.

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 opens with a specific verb and resource ("Get your account details") and immediately enumerates the scope: plan tier, credit limits, usage. That scope is distinct from every sibling (get_changes, get_market, get_ohlcv, get_schema, get_search, get_summary, get_universe), none of which touch account/billing state.

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 implied rather than stated — the agent can infer "call this when you need plan or quota information," but there is no explicit when-to-call trigger (e.g., before hitting rate limits) and no exclusions. This is partly excusable because no sibling overlaps in purpose, so there is no real alternative to route between.

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