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

Annotations only cover the read-only/open-world/idempotent profile; the description adds substantial context beyond them — that the call is paid ($0.007 USDC on Base, Polygon, or Arc), the exact two-step x402 handshake, and the full metric set returned. This is precisely the kind of cost and invocation behavior annotations cannot express.

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 dense sentences that front-load the paid nature and pricing before the payload and payment mechanics. Every clause contributes, though the parenthetical payment instruction is fairly packed and could be slightly tightened.

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 an output schema present, the return values need not be explained, and the description covers cost, currency, assets, and payment flow. It is complete enough to call correctly; the only gap is the absence of any relationship to the sibling signal/basket tools.

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 description coverage is 100% and the single optional 'vault' parameter is already documented in the schema, so the baseline of 3 applies. The description adds nothing about the vault parameter (e.g., how it tailors the signal), leaving the schema to carry the load entirely.

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 and resource: it returns the whole stock basket's rebalancing signal, enumerating returns, volatility, RSI, trend, relative strength, and inverse-volatility target weights for four named tickers. The purpose is unambiguous, but it never distinguishes itself from siblings like stocks_basket, stocks_rebalance, or stocks_signals_prepare, so an agent must infer the split.

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 payment procedure is spelled out (call once to receive the x402 PaymentRequired, then call again with the signed payment in _meta["x402/payment"]), which is genuinely useful invocation guidance. However, there is no guidance on when to choose this over stocks_basket or stocks_signals_prepare, so usage relative to alternatives is only implied.

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