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

Annotations already declare readOnly, idempotent, open-world and non-destructive behavior, so safety is covered. The description adds genuinely useful context the annotations cannot: that yearHigh/yearLow are a trailing 12-13 month feed range and that the quote does not date its extremes, which prevents a common misinterpretation.

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?

Purpose is front-loaded, followed by supported symbols and the trailing-year caveat, all earning their place. The trailing 'Args: symbol' block mildly duplicates the schema description, a small redundancy.

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 usefully explains the trickiest returned fields (yearHigh/yearLow) and their caveats. It stops short of enumerating other expected quote fields such as price or change, leaving a modest gap for a data-returning tool.

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% and the schema already documents the symbol parameter with examples, so the baseline is 3. The description's symbol list and example complement but do not extend the schema's meaning.

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 (returns) and resource (real-time price quote) scoped to a single cryptocurrency symbol, and names the concrete unit of exchange (BTCUSD, ETHUSD, etc.). An agent can distinguish it from get_all_crypto_quotes (all symbols) and get_crypto_historical without opening either schema.

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?

Explicitly routes to get_crypto_historical for year-to-date, calendar-year, dated-extreme or exact 52-week needs, which is a real alternative-selection rule. It does not address when to prefer this over get_all_crypto_quotes, but the single-symbol scope makes that inference trivial.

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