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

Beyond the readOnlyHint annotation, the description discloses the exact return fields ({coin, price, source, age_secs, ts}), states it provides a live exchange mid, and mentions free tier/public data. This adds valuable behavioral context without contradicting 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 dense and front-loaded with 'TRUTH ANCHOR' and 'canonical', immediately conveying the tool's significance. Each sentence earns its place: defining the price, listing return fields, giving usage guidance, and adding caveats. No wasted words.

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 (one parameter, no output schema), and the description covers the return payload, usage context, and limitations. However, the lack of clarity on the 'coin' parameter format leaves a notable gap, preventing a perfect score.

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 has only one parameter 'coin' with no enum or description. The tool description merely says 'for a coin' but does not specify the expected format (e.g., ticker vs name vs internal ID). With 0% schema coverage, the description fails to compensate, leaving the parameter ambiguous.

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 that get_price returns the canonical current price (live exchange mid) for a coin and explicitly positions it as the single source of truth, distinguishing it from sibling tools like get_prices. The verb+resource is specific and unambiguous.

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 gives explicit usage guidance: 'Use this to sanity-check any analytic payload' and warns that if another tool's spot disagrees materially, that tool's price is stale and should be discounted. This provides clear when-to-use versus alternatives, even though no alternative is named.

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