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

Beyond the readOnlyHint=true and idempotentHint=true annotations, the description reveals the fallback order (Coinbase, Kraken, Pyth Hermes), the fact that the serving venue is returned, that Pyth confidence is provided when applicable, and the cost (0.001 USDC per call). No contradiction exists; the description enriches the agent's understanding of side effects and constraints.

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 zero fluff. The primary use case is front-loaded, followed by return details, fallback mechanism, supported assets, and cost—all in a logical, compact flow. Every sentence earns its place.

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 single parameter with full schema coverage, the presence of an output schema, and annotations covering safety, the description is complete. It tells the agent when to use it, what it returns, the cost, and edge cases (declined for unsupported symbols). No additional information is needed for correct invocation.

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 description for 'symbol' already covers the accepted values (SOL, BTC, ETH) and the default. Since schema coverage is 100%, the description adds no additional parameter-level detail. The baseline for full coverage is 3; there is no extra value to push it higher.

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 ('returns a spot price'), a clear resource (spot price), and explicitly notes it avoids venue selection. It names the assets served (SOL, BTC, ETH) and contrasts with alternatives (get_sol_price, get_btc_price) by emphasizing the 'without choosing a venue' scope. This clearly distinguishes it from its siblings.

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 opening phrase 'Use when an agent needs a spot price without choosing a venue' provides clear guidance on when to invoke this tool. It implicitly suggests that when a specific venue is preferred, other tools should be used, but it does not explicitly name alternative tools. The cost disclosure and supported-asset list add useful context for decision-making.

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