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

Annotations cover read-only and open-world status, but the description adds genuinely new behavioral context that annotations cannot convey: rate limiting (up to 30 calls/minute) and a 15-minute refresh cadence. It does not discuss pagination or error behavior, but for a simple quote lookup this is richer than typical.

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 compact sentences that front-load the free/rate-limited copy framing and then the contrast with the paid live tool. Every clause carries distinct information — staleness, rate limit, cost, and refresh frequency.

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 one-parameter read-only lookup with no output schema needed, the description supplies everything required to select and call it correctly: what it returns, how fresh it is, how fast it can be called, and what the alternative costs.

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% — the single 'tokens' parameter is documented with format, example, and the 50-ticker cap. The description adds no parameter guidance beyond that, 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 states that this returns the same answer as the sibling 'prices' tool, which identifies the resource (price quotes) and its scope. It does not use an explicit verb like 'get' or 'list,' but the sibling reference and the 'free copy' framing make the function understandable at a glance.

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 tradeoff against the sibling is spelled out clearly: 15-minute staleness and 30 calls/minute here versus live-per-minute data on 'prices' for USD 0.003. An agent can therefore choose between them by freshness and cost, though no explicit 'use this when' clause is present.

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