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

With no annotations provided, the description carries the full burden. It discloses that the tool is paid, requires a signature, is not self-serve, and points to the catalog for details, which covers access requirements. However, it does not describe the output format, side effects (e.g., read-only nature), or error behavior, leaving some behavioral ambiguity.

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 composed of four concise sentences, each delivering distinct information: what it is, when to use it, the access constraint, and where to find more details. It front-loads the purpose and avoids redundancy, with no filler or unnecessary technical jargon.

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 has no output schema, the description should clarify what the response contains. It mentions 'monthly performance series' but not the structure or format of the data, and doesn't describe pagination or any return envelope. It compensates somewhat by directing to the catalog for availability and price, but for a data-retrieval tool, more detail on the returned dataset would be expected.

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 sole parameter (payment_signature) is fully documented in the input schema with a detailed description ('x402 payment authorization for MCP 2026 header-aware clients'). The tool description adds no additional parameter guidance, but since schema coverage is 100%, the baseline score of 3 applies—the schema already provides the necessary meaning.

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 identifies the tool as a 'Paid signed RCQ BTC monthly performance series' for historical review, audit, and research, which clearly conveys its purpose. It differentiates from siblings by emphasizing the 'complete currently published monthly dataset' and noting that the separate access-key subscription applies only to monthly_series, though it doesn't name an alternative verb or resource explicitly. It is not tautological and provides a specific subject.

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?

It explicitly states use cases ('historical review, audit and research workflows that require the complete currently published monthly dataset') and warns that access is not self-serve via MCP, directing users to rcq://catalog for availability and price. It lacks an explicit 'when not to use' or named alternative tool, but the guidance is clear enough to determine appropriate invocation.

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