Katzilla MCP

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

The description adds valuable behavioral context beyond the annotations. Annotations indicate read-only, non-destructive, idempotent, and open-world hints, but the description elaborates on the return format ('Katzilla envelope { data, quality, citation }'), explains quality metrics ('freshness/uptime/confidence'), and details citation components ('source URL, license, SHA-256 hash'). This enriches the agent's understanding of the tool's behavior and output structure.

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 highly concise and well-structured, consisting of two sentences that efficiently convey purpose, source, and return format. Every sentence adds critical information without redundancy, making it easy for the agent to parse and understand the tool's functionality quickly.

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 complexity (search operation with structured output), rich annotations (read-only, etc.), and the presence of an output schema, the description is complete. It explains the purpose, source, and return format in detail, compensating for any gaps and ensuring the agent has sufficient context to use the tool effectively without needing to infer missing information.

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 100% schema description coverage, the input schema already fully documents the two parameters ('query' for library name and 'limit' for max results). The description does not add any additional semantic details about these parameters, such as examples or constraints beyond the schema. Thus, it meets the baseline of 3 by not detracting from the schema's completeness.

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: 'Search JavaScript libraries on cdnjs CDN.' It specifies the verb ('Search'), resource ('JavaScript libraries'), and platform ('cdnjs CDN'), making it distinct from sibling tools that focus on other domains like agriculture, crime, or economics. This precise articulation helps the agent understand exactly what this tool does.

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 searching JavaScript libraries on cdnjs. It mentions the source ('cdnjs (Free API), updates monthly'), which implies it's suitable for up-to-date but not real-time data. However, it does not explicitly state when not to use it or name alternatives among siblings, such as other library search tools, which prevents a perfect score.

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