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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds that both gainers and losers rows are returned with quote values, but says nothing about rate limits, data freshness, or pagination. Useful but thin beyond what annotations provide.

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 tightly written sentences with zero waste; the core purpose leads and the routing guidance follows. Nothing is redundant.

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?

With an output schema present, return values need not be explained, and the safety profile is covered by annotations. The description is essentially complete for a simple read tool, with only minor ambiguity (limit is actually per-section, per the schema, while the description says 'caps the list').

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 both parameters are fully documented in the schema (limit 'Rows per section', vs_currency with allowed values). The description restates their roles ('quote values in vs_currency', 'limit caps the list') without adding syntax or format detail. 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?

States a specific verb ('Fetch') and resource ('crypto gainers and losers rows'), and explicitly contrasts with siblings coingecko_markets and coingecko_trending. An agent can distinguish this tool's scope without opening a schema.

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?

Names two alternative tools and the exact condition that selects each: broader market rankings vs. recently popular assets. This is explicit when-to-use/when-not guidance rather than inference.

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