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

With no annotations, the description carries the burden of disclosure. It adds a cost mention ('10 sats per call') and notes real-time data, providing some transparency. However, it does not describe the output format, error behavior, or rate limits.

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 two short sentences, front-loaded with the main purpose and enriched with the cost detail. Every word earns its place with no redundancy.

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 zero-parameter price ticker tool, the description is nearly complete. It names the asset and currencies and notes the cost. The only minor gap is explicitly stating the output structure, but the implied response (prices for the three currencies) is sufficient given the simplicity.

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?

There are zero parameters, and the schema is empty. The description correctly highlights the fixed nature of the tool (returns prices in three specified currencies), so no parameter explanation is needed. Baseline of 4 applies.

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 provides real-time BTC price in USD, EUR, and BRL. It is specific and distinct from sibling tools, which cover broader domains like search, sentiment, and translation.

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?

Usage context is implied rather than explicit. The description indicates the tool is for obtaining BTC prices, but does not mention when to prefer it over alternatives or any exclusions. It is sufficient for a simple no-parameter tool.

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