btc_price

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

With no annotations, the description provides the daily call limit and free status. This is helpful but does not disclose the return format or any side effects. For a simple price query, this is minimally adequate.

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 very short, which is concise, but the inclusion of 'Free/call (free: 5/5 today)' is somewhat cryptic and could be clearer. It front-loads the essential info but the parentheses could be confusing.

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 tool's simplicity and lack of parameters, the description covers the main purpose and usage limit. However, without an output schema, the agent does not know the format of the returned data, which could be improved.

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 tool has no parameters, and the input schema is empty. Per the guidelines, 0 parameters gets a baseline of 4. The description adds the free pricing info, which is relevant.

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 'BTC real-time price' which directly indicates the tool's function. However, it does not explicitly distinguish it from sibling tools, but given that no other sibling is related to Bitcoin price, the purpose is fairly clear.

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 mentions it is free and provides the daily call limit, which gives some usage context. However, it does not specify when to use this tool versus alternatives, nor does it mention any prerequisites or situations to avoid its use.

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