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

Annotations already establish this as a safe, read-only, idempotent operation. The description adds meaningful behavior beyond that: it clarifies that "trending" is attention-based rather than price-based, states the tool "Takes no parameters," and discloses the entry counts per category. This gives an agent an accurate mental model of what the response means.

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 front-loaded with the core purpose and immediately gives concrete counts, then adds the key usage distinction. Every sentence earns its place, and no filler or redundant restatement of the title appears.

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 zero-parameter, read-only endpoint with an output schema available, the description is complete: it explains what the data means, what it contains, when to use it, and which sibling to prefer for a different need. Nothing an agent needs to make the correct invocation 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 tool has zero parameters and the input schema is empty, so there is no parameter burden to carry. The description explicitly says "Takes no parameters," which removes any doubt, though the schema alone is already sufficient here. This is at the baseline for a no-parameter tool with a slight confirmation benefit.

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 states a specific verb and resource: "CoinGecko's current trending board, ranked by search activity on CoinGecko itself." It enumerates the exact contents (`coins` 15, `nfts` 7, `categories` 6) and explicitly separates this tool from `get_coingecko_coins_markets`, so an agent can tell it apart from siblings without ambiguity.

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 gives an explicit when-to-use rule: "Use it as a discovery entry point when the user named no specific asset." It also names the alternative for price-driven rankings: "for movers ranked by market data use `get_coingecko_coins_markets` ordered by volume," making the selection criteria unambiguous.

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