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 readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, but the description discloses that the source 'updates daily' (implying freshness considerations) and details the return format ('Katzilla envelope { data, quality, citation }') with explanations of quality scores and citation contents. This enriches the agent's understanding of data reliability and output structure, though it doesn't cover rate limits or auth needs (not required here).

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 and front-loaded: the first sentence states the core purpose, followed by category details, source information, and return format explanation. Every sentence adds value (e.g., source credibility, output structure), with no redundant or verbose content, making it highly concise and well-organized.

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 low complexity (one optional parameter), high schema coverage (100%), rich annotations (covering safety and idempotency), and presence of an output schema (implied by 'Returns the Katzilla envelope'), the description is complete. It adds necessary context like source updates, return format details, and data quality aspects, ensuring the agent has sufficient information without over-explaining structured fields.

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 input schema has 100% description coverage, with the 'category' parameter fully documented in the schema (including examples). The description lists the same categories in its text, adding no extra semantic meaning beyond what the schema provides. Since schema coverage is high, the baseline score of 3 is appropriate, as the description does not compensate with additional parameter insights.

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 a random emoji from EmojiHub, optionally filtered by category.' It specifies the verb ('Get'), resource ('emoji'), and scope ('random' with optional category filtering). It distinguishes itself from sibling tools (e.g., culture__aic-artworks, culture__bible-api) by focusing on emoji retrieval, making the purpose highly specific and differentiated.

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 usage: it mentions the optional category filtering and lists all available categories (e.g., 'smileys-and-people', 'animals-and-nature'). However, it does not explicitly state when to use this tool versus alternatives (e.g., other culture tools like culture__colormind or culture__free-dictionary) or any exclusions, so it lacks explicit sibling differentiation beyond the purpose statement.

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