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

readOnlyHint=true and openWorldHint=true already carry the safety profile, so the description only needs to add behavioral color. The phrase 'current coin lookup, not a trading feed' usefully signals snapshot vs. live data, but no auth needs, rate limits, or freshness caveats are mentioned.

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 sentences, zero filler, with the core capability first and the routing hint second. Nothing is wasted or 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 two-parameter read-only lookup with an output schema present, the description covers purpose, scope, and the main alternative, so return-value detail is correctly omitted. Only the broader sibling landscape (markets/search) is left implicit.

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% and vs_currency's only allowed value (usd) is spelled out in the schema. The description restates 'one coin id' and 'requested quote currency' but adds no format guidance beyond what the schema already provides, so 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?

Specific verb (Fetch) plus resource (CoinGecko profile and market data for one coin id) with the quote currency scoping named. It explicitly disambiguates itself from the sibling coingecko_coin_analysis, so an agent can route without opening either 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?

Clear when-not guidance ('not a trading feed') and a named alternative for chart analysis ('use coingecko_coin_analysis'). It doesn't address other nearby siblings like coingecko_markets or coingecko_search, but the primary ambiguity is resolved.

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