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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds only a cost signal (the injected pricing note of $0.008 per successful request), which is genuinely useful behavioral context, but says nothing about rate limits, auth, 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 opening sentence is front-loaded and efficient, but roughly half the text is an injected pricing boilerplate block that is unrelated to tool selection. The core content earns its place; the wrapper does not.

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?

An output schema exists, so return values need not be spelled out, and the description still previews the returned fields. With annotations covering safety and 100% schema coverage, the only real gap is the absence of routing guidance versus sibling historical-data tools.

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 all three parameters (id, date, localization) are already documented with defaults and formats in the schema. The description adds no extra syntax or constraint beyond what the schema provides, so the baseline 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 names a specific verb (query) and resource (historical data for a coin by coin ID) and enumerates the returned fields (price, market cap, 24hrs volume). It is clear on its own, but it does not differentiate itself from close siblings such as get_coingecko_coins_id_market_chart_range or get_coingecko_coins_id_ohlc, which also return historical data.

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 phrase 'at a given date' implicitly distinguishes this from the range-based siblings, so the intended usage is inferable. However, there is no explicit statement of when to prefer this over market_chart_range/ohlc, and no prerequisites or exclusions are given.

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