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

Annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety. The description adds meaningful behavioral context: it returns `prices`, `market_caps`, and `total_volumes` as timestamp-and-value pairs in milliseconds, and clarifies the trailing-window semantics. No contradiction.

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?

Three sentences with no filler: core function, parameter roles, return shape, and selection guidance are all present. Every clause contributes to the agent's understanding.

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?

Covers the essential calling context: token identification, trailing window, output structure, and when to choose the range sibling. An output schema exists, so deeper return details are available there, and nothing important 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?

Schema coverage is 100%, so the schema already documents all parameters. The description adds value by relating `id` to asset platform and `contract_address` to the token, and by clarifying that `days` sets the trailing window, which is slightly more semantic than the schema entries alone.

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 and resource: retrieves historical price/market-cap/volume series for a token identified by contract address over a trailing window. It distinguishes itself from siblings by naming the id-based market chart and the range-based chart, so an agent can tell them apart.

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?

Explicitly instructs 'Use it when you have an address rather than a CoinGecko id' and points to `get_coingecko_token_market_chart_range` for explicit start/end. Also references the same shape as `get_coingecko_coins_id_market_chart`, clarifying when the id-based alternative is appropriate.

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