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

Beyond the readOnly/openWorld annotations, it discloses important behavior: public endpoint, last-price-only scope, $0.002 USDC cost per successful call via x402, and no charge on failure. These are material operational details an agent needs.

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 front-loaded and compact: resource, scope, endpoint, then pricing. Every sentence adds useful information with no filler.

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 simple one-parameter, read-only, paid ticker tool with an output schema and safety annotations, the description covers what it returns, the source, cost, and failure charging behavior. No critical invocation context 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% and the market parameter is already documented with an example. The description reinforces 'one market such as BTC-EUR' but adds no format or validation detail beyond the schema.

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 names a specific resource (Bitvavo market last price), a concrete example (BTC-EUR), and the source endpoint. The exchange name makes it distinguishable from the many sibling exchange-specific ticker 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?

It implies usage for a single Bitvavo market and clarifies that only last price is returned. However, it does not explicitly state when to choose this over other exchange ticker tools or when not to use it.

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