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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety. The description adds useful behavioral context: the default series (price), the default interval (hourly or daily), ordering (oldest first), and the nature of each series (e.g., intraday funding/OI, daily archive, whale flows). This goes beyond annotations without contradicting them.

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 sentence that efficiently packs the core purpose and all four series definitions. It's front-loaded with 'History for one coin' and avoids filler. While dense, every phrase adds information, making it appropriately concise for the complexity.

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 and fully documented parameters, the description covers the main decision point (which series to use) and default behavior. It doesn't mention pagination or detail modes, but those are described in the parameter fields. The description is sufficient for an agent to call the tool correctly without missing key information.

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 parameters like coin, days, limit, etc., are already documented. The description enriches the 'series' parameter by explaining what each enum value returns (e.g., 'near-live hourly or daily bars', 'intraday open interest and funding path'). This adds semantic value beyond the schema's simple 'Which lane; see the description.'

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 states 'History for one coin' and enumerates the available series (price, funding_oi, daily, whale_daily), each with a brief explanation. This is specific and goes beyond a mere tautology. It doesn't explicitly contrast with sibling tools, but as the only 'history' tool it's distinct enough.

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?

No guidance is provided on when to use this tool versus alternatives. The description only explains what it does, not the conditions for selecting it over other tools like market_now or coin_brief. There's no mention of when to prefer this tool or exclusions.

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