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

Beyond the readOnly/openWorld annotations it discloses material behavior: prices are delayed or end-of-day per Yahoo (data freshness), and it states the paid-call model ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls not charged). That cost and freshness disclosure is exactly the kind of context annotations cannot carry.

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 dense sentences: capability and scope first, limitations second, cost last. No filler, and the most decision-relevant constraints are front-loaded.

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, return values need no explanation, and the description covers what remains: data freshness, coverage limits, and the payment requirement. Nothing an agent needs to invoke it correctly 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%, so both parameters and the full range enum are already documented in the schema. The description adds only the asset-class enumeration, which largely duplicates the symbol examples already in the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 names a specific verb and resource ('quote and daily history for one ticker') and pins the source to Yahoo's public chart endpoint, which separates it from the many other price/history siblings. It also enumerates supported asset classes (stocks, ETFs, indices, FX, crypto), so an agent can tell what it covers. It stops short of explicitly naming which sibling to use for the cases it doesn't cover.

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 gives a clear scope boundary — 'no fundamentals or company lists are included' — which tells the agent when to look elsewhere, plus the range parameter implies both spot quote and history use. There is no explicit 'use X tool instead' routing, so the agent must infer the alternative from the 100+ siblings.

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