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

Annotations already establish read-only, non-destructive, closed-world behavior, so the safety profile needs no repetition. The description adds genuinely useful semantics the annotations cannot carry: the pip deltas are signed by actual price direction and are not pre-adjusted for side, plus the returned field shape. It stops short of describing edge cases or constraints on delta ranges.

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?

Three tight sentences: the core computation first, the trigger phrase second, the return shape last. Zero filler, and the sign-convention caveat is embedded where the agent will read it rather than buried.

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 present, the description usefully names scenarios[] and its fields, and it pins down the sign convention that would otherwise cause wrong calls. It omits any mention of pip definition per pair or limits on the delta list, which are minor given the pip-value siblings exist.

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?

Schema coverage is only 60%, so the description must compensate, and it does for the two riskiest parameters: it clarifies that deltasPips are raw signed moves and that a single side (long or short) applies per call. It does not address entryPrice or units beyond what the schema already states, leaving some coverage gap.

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 computation (PnL across a range of hypothetical pip moves) for a specific resource (a single forex position, long or short), which an agent can distinguish from the many sibling workflow tools. It does not, however, explicitly contrast itself with the closest siblings such as run_forex_pnl or run_scenario_planning, so differentiation is left to inference.

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?

Provides a concrete trigger phrase ("what if price moves X pips in either direction?") that tells the agent when to reach for this tool. There is no explicit when-not guidance or named alternative (e.g., use run_forex_pnl for a single realized PnL), so routing among the dense set of forex siblings is only partially supported.

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