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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), so the bar is lower. The description adds real value beyond them by disclosing data provenance ('Source: mempool.space') and freshness ('Real-time'), which an agent needs to judge trustworthiness and staleness. It stops short of stating caching behavior, update cadence, or which currencies are actually returned.

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 tight sentences with the core capability front-loaded, followed by provenance and freshness. No filler or repetition; every clause carries information.

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 read-only tool with no parameters and no output schema, the description covers what is returned (price in USD and other major currencies), the source, and the freshness. The only gap is that 'other major currencies' is unspecified, leaving the exact return shape slightly ambiguous.

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 takes zero parameters, so per the baseline there is nothing for the description to disambiguate. No parameter syntax or defaults are needed, and the description correctly spends no words on inputs.

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?

States a specific verb and resource ('Get the current Bitcoin price') plus scope ('in USD and other major currencies'). No sibling tool overlaps with price lookup, so an agent can distinguish it immediately from btc_send_decision or optimal_send_window.

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 implies usage (a live price lookup) but never states when to reach for this versus related Bitcoin tools like optimal_send_window or btc_send_decision. Since it is a zero-parameter, single-purpose tool the implied context is largely sufficient, but no explicit routing guidance is given.

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