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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered. The description adds meaningful behavioral context: it warns of the large payload ('roughly 18,000 entries'), the latency ('takes several seconds'), and recommends caching. This goes beyond the annotations by exposing performance and resource implications, though it could also mention rate limiting or response size caps.

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 compact yet information-dense. It fronts the core purpose, then naturally flows into usage guidance, a concrete example ('bitcoin, not BTC'), performance caveats, and alternatives. Every sentence adds distinct value; there is no filler or redundancy.

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 tool with a single optional parameter and an existing output schema, the description is complete. It covers what the tool returns, how to use it, why caching is needed, and which sibling tool to use instead in different scenarios. Nothing an agent needs to invoke it correctly 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 schema already covers the single parameter with a description ('Include platform + contract addresses.') and 100% schema coverage. The description's mention of include_platform ('Set include_platform to also get each coin's contract address per chain') reinforces the schema but does not add new semantic detail. This matches the baseline of 3 for high schema coverage.

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: 'The full CoinGecko identifier map: every listed coin as id, symbol and name.' It clearly distinguishes itself from siblings by explaining that it resolves tickers to ids, and explicitly contrasts with get_coingecko_simple_price and get_coingecko_token_data. An agent immediately knows what this tool produces and how it differs from related tools.

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 explicit guidance on when to use this tool ('Use it once to resolve a ticker into the id') and when not to ('If you already know the ids and only want numbers, call get_coingecko_simple_price directly; to identify a coin from a contract address instead, use get_coingecko_token_data'). It also advises caching due to the large response. This leaves no ambiguity about the correct invocation context.

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