Katzilla MCP

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true. The description adds valuable behavioral context beyond annotations: 'Rich card data with images, prices, and legality,' 'Source: Scryfall (Scryfall Terms), updates daily,' and details about the return envelope structure (quality scores, citation with URL/license/hash). This provides important operational context about data freshness, licensing, and auditability.

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: first sentence states purpose and capabilities, second describes data richness, third covers source and update frequency, fourth explains return format. Every sentence adds value with zero waste, and it's appropriately front-loaded with core functionality.

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 comprehensive annotations, 100% schema coverage, and an output schema (implied by the return envelope description), the description provides complete context. It covers purpose, usage modes, data characteristics, source attribution, update frequency, and return format - addressing all necessary aspects for this search/retrieval tool.

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?

Schema description coverage is 100% with the query parameter well-documented in the schema. The description adds minimal parameter semantics beyond the schema, only implying the query supports 'Scryfall syntax' and that omission triggers random card mode. This meets the baseline 3 since the schema does the heavy lifting.

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 Magic: The Gathering cards via Scryfall' with specific verbs (search, returns) and resource (cards). It distinguishes from siblings by specifying the domain (Magic: The Gathering) and data source (Scryfall), which none of the other fun__* tools cover.

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 explicit usage guidance: 'Supports full-text search or returns a random card' and specifies 'Omit [query] for a random card' in the schema. It clearly indicates when to use (search or random retrieval) and how to trigger each mode, with no alternatives needed among siblings.

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