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

With no annotations, the description carries the full burden and does so: it names the pricing model and cost ($0.005 USDC per call via x402), the two failure modes (400 on bad input, 502 when volatility is uncomputable) and that neither is charged. It also discloses the underlying method (14-day ATR, normal approximation, reflection principle), which sets expectations on accuracy.

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?

Front-loaded with the core definition in the first sentence, followed by method, validation and pricing. There is mild redundancy between the opening sentence and the following clause, and the statistical parenthetical is dense, but nothing is wasted outright.

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?

There is no output schema, so the description must convey return values; it does partially by naming the horizons (1, 7, 30 days) and the separate touch probability. It still leaves the response shape and unit convention (% vs fraction) unspecified, a minor gap for a two-parameter read tool.

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 100% and an enum already constrains symbol, so the schema does most of the work. The description still adds value by tying the constraint to behavior: an unsupported symbol or non-positive target returns 400 and is not billed, which the schema cannot express.

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 and its output semantics: probability of closing beyond a target at 1, 7 and 30 days plus a touch probability. No sibling (get_support_resistance, get_signal_bias, get_trade_plan) produces a probability of this kind, so it is unambiguous which tool to select.

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?

Gives concrete prerequisites: symbol must come from list_symbols and target must be positive, with the failure consequence spelled out. It does not explicitly contrast with alternatives such as get_support_resistance or get_trade_plan for related questions, so usage context is clear but exclusions are absent.

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