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

Annotations already declare readOnly, idempotent, and closed-world, so safety is covered. The description adds genuinely new behavioral context the annotations cannot express: the call is paid at $0.005 USDC via x402, which materially affects an agent's decision to invoke it. Rate limits and failure behavior are not mentioned, but the pricing disclosure is the key addition.

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: what it returns, when to use it, and the cost/discovery prerequisites, in that order. Every clause carries information and nothing is repeated.

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 compensates by listing the returned fields, and it covers the two non-obvious prerequisites for this tool: payment and asset discovery. For a single-parameter read tool with annotations present, nothing an agent needs before calling is missing.

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 'asset' parameter is already documented with examples (BTC, ETH, SOL, trend-btc) and a pointer to list_assets. The description only restates 'one crypto asset', adding no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 gives a specific verb and resource ('Get the daily trend signal for one crypto asset') and enumerates the returned fields (signal, exposure, SMA50, 30-day volatility, close, dates). It does not explicitly distinguish itself from the sibling get_signal, though the 'directional/exposure view' phrasing implies the difference.

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?

It states the triggering condition ('Use when you need a directional/exposure view for a specific asset') and routes asset discovery to list_assets, which matches the schema hint. It stops short of naming when to prefer get_signal, get_regime, or get_indicators instead, so the sibling routing is only partially covered.

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