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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety and determinism profile is covered. The description adds the meaningful behavioral detail that results are in USD and include a 24h change window, but says nothing about batch behavior, error handling for invalid ids, or rate limits on the upstream API.

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 short sentences, front-loaded with the output contract before the identifier convention. No filler and nothing buried.

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 tool with full schema coverage and annotations, this is close to sufficient: the agent knows the input format and exactly what comes back. Minor gaps are how batched ids map to results and what happens with an unknown id.

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 single parameter's description already specifies comma-separated CoinGecko ids with an example. The description's example repeats what the schema provides, so it adds no semantics beyond the baseline for fully documented schemas.

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 resource and output: current USD price plus 24h percent change for one or more coins. It is clearly distinguishable in substance from ohlc, market_overview, and coin_profile, though it never names those siblings to make the distinction explicit.

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?

Gives identifier-format guidance (CoinGecko slugs like bitcoin, ethereum, solana) but no when-to-use or when-not-to-use guidance, and no routing advice relative to siblings such as ohlc or market_overview. Usage is only implied by the tool's function.

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