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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds meaningful behavioral detail beyond those annotations: response is keyed by lowercase contract address, field names derive from the quote currency, and inclusion of market cap, volume, change, and last-updated fields depends on the corresponding include flags.

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?

Four sentences, each with a distinct purpose: core operation, key parameter semantics, response shape, and alternative routing. It is dense but not redundant, and front-loads the most important distinguishing fact.

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?

Given the annotations, output schema, and the description's coverage of required parameters, response format, and sibling tool alternatives, nothing essential is missing. An agent has enough to select and invoke the tool correctly.

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 description adds real meaning to id, contract_addresses, and vs_currencies, and explicitly ties all four include_* booleans to response fields. Precision is not covered in the description, but the schema documents it adequately, so the description still adds value above the structured data.

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 identifies a precise operation — price lookup keyed by contract address rather than CoinGecko id — and clearly differentiates it from siblings like get_coingecko_simple_price and get_coingecko_token_data. The first sentence immediately distinguishes it on the key dimension that matters.

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?

It explicitly states when to use the tool: when you hold an address and no id. It also names the two alternatives and the conditions that select them, so an agent receives direct routing guidance rather than having to infer it.

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