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

Annotations only cover readOnlyHint and openWorldHint. The description adds real operational context the annotations do not: an x402 payment requirement of $0.003 USDC per call, a DEX-only coverage limitation, and a 500-point cap. It still doesn't say whether data is real-time or delayed, or whether payment failures are handled.

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 compact sentences, correctly front-loaded with what the tool returns before the constraints and cost. The cost sentence earns its place; only the interval/point details feel slightly compressed against the schema.

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-shape burden and does so by naming OHLC and percent change. It also discloses cost and coverage limits. The remaining gap is sibling differentiation and the meaning of the chain/address inputs.

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 75%, so the baseline is 3. The description usefully extends the interval range to 1w (the schema only lists 5m/1h/4h/1d as examples) and confirms the 500-point ceiling, but it says nothing about the chain enum or the required address parameter.

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 (price history time series for a token contract) and enumerates the returned fields (OHLC + percent change) plus the resolution range. However, it never distinguishes itself from close siblings like crypto_candles, token_price, or chart, which an agent must disambiguate among.

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?

"Works for DEX-only tokens" is a genuine applicability constraint, and the per-call cost hints at when the call is worth making. But there is no explicit when-to-use/when-not guidance, and the overlapping siblings (crypto_candles, token_price, chart) are never named or excluded, leaving selection to inference.

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