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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is clear. The description adds meaningful behavioral context beyond this: it names the external API (CoinGecko), states the default pair (ETH/USD), and confirms no payment or wallet is required. There is no contradiction with the annotations.

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 a single, tightly written sentence that front-loads the core purpose and includes only high-value context (source, cost, defaults). Every phrase contributes meaning, making it an example of effective brevity.

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?

The tool is simple: two optional, well-documented parameters and an output schema, so the description does not need to explain return values. It provides the essential context—external API, free usage, and default behavior—making it complete for an agent to select and invoke the tool appropriately in most cases.

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 input schema covers 100% of the parameters, with both 'symbol' and 'vsCurrency' having clear descriptions and default values. The description's mention of 'Defaults to ETH/USD' reinforces but does not extend beyond what the schema already states, so it meets the baseline but adds no new semantic value.

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 clearly states the tool's function: 'Get a spot token price from a public market API (CoinGecko).' It specifies a concrete verb, resource, and source, and notes the default pair. However, it does not explicitly differentiate from the sibling tool 'market.crypto', so it misses the highest bar for sibling distinction.

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 implies when to use the tool (for a spot token price) and adds useful context such as 'Free — no payment or wallet needed.' It does not provide explicit guidance on when not to use it or mention alternatives like 'market.crypto' for broader market data, leaving usage somewhat implied.

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