Track an account's equity curve and drawdown over time

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

Beyond the annotations (readOnlyHint, openWorldHint), the description discloses key behavioral traits: the series is downsampled to at most 200 points, but first/last/deepest-drawdown points are always retained. It explains the `notes` field records downsampling and warns that short moves may not be visible. It also tells users to read `caveats` and `portfolioCaveats` before quoting numbers, which is critical for data quality.

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?

The description is dense but well-structured: purpose first, then alternatives, then downsampling behavior, then parameter clarifications. Every sentence adds value, though the length is substantial. The all-caps 'THIS RESPONSE IS SHAPED' is attention-grabbing but slightly jarring; however, it emphasizes an important limitation. Overall it's appropriately sized for a tool with these nuances.

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?

Given the output schema exists and annotations are present, the description covers all necessary operational context: how the response is shaped, downsampling rules, the meaning of `notes` and `caveats`, and parameter gotchas. It leaves no major ambiguity about selecting, invoking, or interpreting the tool's results.

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 input schema already describes parameters, but the description adds crucial disambiguation: `accountId` is the `id` field from list_accounts (NOT `login`), and `reporting` is an ISO-4217 currency code, not a reporting period. It also notes omitting from/to gives the last 30 days. These clarifications prevent common misuse and go well beyond the schema's stated descriptions.

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 starts with a specific verb and resource: 'Return the reconstructed equity curve and floating drawdown for one MT5 account over a date window, as a series of points.' It clearly distinguishes from siblings by naming get_account_performance for whole-account figures and get_performance_breakdowns for day/symbol/hour breakdowns, so the tool's role is 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?

Explicit guidance says when to use it ('how has my equity moved' or 'what was my worst drawdown') and when not to (for net P&L, win rate, ROI use get_account_performance; for breakdowns use get_performance_breakdowns). It also adds practical tips like omitting from/to for the last 30 days and narrowing the window for finer resolution.

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