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

Annotations already declare read-only, idempotent, open-world, non-destructive. The description adds pricing behavior ($0.02 per call over x402 on Base, prepaid x-credit-token header for unlimited calls, 1 free call/day, no API key) and that the reference price can freeze when the US market is shut — behavior an agent needs to know. It does not describe error cases or freshness guarantees beyond reference age.

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-loads the core question, which is good, but the single long sentence chains many clauses and includes pricing/access boilerplate and a disclaimer in the same breath. It is information-dense but not well structured; some content (x402 pricing details) belongs in a separate note.

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?

For a read-only tool with an output schema, the description covers the essential scoping (frozen reference, 24/7 Base trading), the return contents, and selectable amountUsd impact. Output schema handles return format. Minor gaps: no explicit guidance on when a frozen reference matters or what the dividend announcement field implies.

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%, so the schema documents both symbol (NVDA, NVDAc or token address) and optional amountUsd. The description mentions amountUsd in the context of 'rough impact for amountUsd' but adds no format or usage detail beyond the schema. Baseline 3 is appropriate.

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 question: whether the Base price of a tokenized stock is fair right now and whether the reference is frozen. The verb and resource are clear, and the scope (every Coinbase-listed stock, 24/7 on Base) distinguishes it from siblings like tokenized_stock_price or stock_position.

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?

Implies usage by describing what one call returns (US session, reference age, DEX premium/discount, pool depth, etc.), but never explicitly says when to use this instead of tokenized_stock_price, stock_position, or stock_collateral_risk. The reader must infer the distinction from the return contents.

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