Katzilla MCP

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

The description adds valuable behavioral context beyond what annotations provide. While annotations indicate read-only, non-destructive, idempotent, and open-world characteristics, the description adds that the data 'updates real-time,' specifies the source licensing (AGPL-3.0), and details the output structure (Katzilla envelope with quality scores and citation including SHA-256 hash). This provides important operational context about data freshness, auditability, and source attribution.

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 efficiently structured in two sentences that pack substantial information: the core functionality, data source, output format, and metadata about quality and auditability. Every element serves a purpose with no wasted words, and key information is front-loaded in the first sentence.

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 0 parameters, comprehensive annotations, and an output schema (implied by the detailed description of the return format), the description provides complete context. It covers purpose, source, licensing, real-time nature, output structure, quality metrics, and audit features—everything needed to understand and use this tool effectively.

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?

With 0 parameters and 100% schema description coverage, the baseline would be 4. The description appropriately acknowledges this by not discussing parameters and instead focuses on what the tool does without inputs. It correctly states that the tool fetches current fees without requiring any parameters.

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's purpose: 'Get current Bitcoin recommended transaction fees from Mempool.space' with specific details about what it returns ('fee rates in sat/vB for different confirmation targets') and distinguishes it from siblings by specifying the data source (Mempool.space) and output format (Katzilla envelope). It uses specific verbs ('Get', 'Returns') and identifies the exact resource.

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 provides clear context for when to use this tool: for obtaining Bitcoin transaction fees from a specific real-time source. It mentions the source (Mempool.space) and that it updates real-time, which helps differentiate it from potential alternatives. However, it doesn't explicitly state when NOT to use it or name specific alternative tools among its siblings.

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