What a coin costs now

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

Annotations already establish readOnlyHint=true, making the safety profile clear. The description adds that the tool optionally returns historical price data ('where it has been'), which is consistent with the schema and annotations, but does not disclose further behavioral traits such as data freshness or response shape.

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?

The description is a single, front-loaded sentence that states the core action and the optional behavior, with a short rationale that earns its place. There is no redundant or filler content.

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 spot-price tool with an output schema and clear annotations, the description covers the essential behavior and optional history sufficiently. It does not elaborate on sibling trade-offs, but no critical call-time fact 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?

The schema already documents history_hours and currency via an enum. The description adds conceptual meaning by matching 'Current price' to currency and 'where it has been' to history_hours, but it does not clarify ranges, units, or behavior when history_hours is omitted beyond what the schema already provides.

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 clearly identifies the resource (a coin) and the action (return its current price), with optional price history. It is specific but does not explicitly differentiate this from sibling tools like get_ticker or get_recent_trades.

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 description implies the tool is used when current price and optionally historical price context are needed, especially 'so a view can be grounded in what actually happened.' However, it provides no explicit exclusions or alternatives, leaving sibling differentiation to inference.

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