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

Annotations already establish readOnly, idempotent and non-destructive behavior, and the description adds genuinely new context beyond them: an API key is required, and part of the payload is entitlement-gated by plan tier. It stops short of describing pagination or how the written findings are produced.

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?

A single dense sentence with the resource and window front-loaded, followed by what is returned and the access requirements. Nothing is wasted, though the mid-sentence tier split makes it slightly harder to scan than a two-clause structure would.

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, the description carries the return-value burden and does it reasonably well by enumerating totals, skill score, win rate and per-dimension breakdowns plus written findings. Auth and entitlement constraints are covered; only return format details are absent.

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?

Only one parameter, and the schema already documents it fully ('1-30, default 30') for 100% coverage. The description's '30-day' framing matches the default but never mentions that the window is configurable, so it adds no meaning beyond the schema.

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?

States a specific verb+resource: a 30-day trading report for 'this account' derived from its own closed trades, plus the exact metric set returned. That cleanly separates it from list-style siblings like paper_trades or paper_equity, though it never names an alternative explicitly.

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 description implies when it is useful (you want aggregated performance analytics for the paper account) and discloses tier gating: totals and skill score are free, the deeper breakdowns and written findings need API Pro or above. It does not tell the agent when to prefer this over paper_equity or paper_trades, so usage is only implied.

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