Sakila MCP Server

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

No annotations are provided, so the description carries full burden for behavioral disclosure. It only states what the tool does ('get rankings') without mentioning any behavioral traits such as whether it's read-only (likely, but not confirmed), performance characteristics, authentication needs, rate limits, or what the output format looks like. For a tool with no annotation coverage, this leaves significant gaps in understanding how it behaves.

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 a single, efficient sentence in Japanese that directly states the tool's purpose without unnecessary words. It's appropriately sized for a simple retrieval tool, though it could be more front-loaded with key details if expanded. There's no wasted verbiage, making it concise and well-structured.

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 (3 parameters, no output schema, no annotations), the description is incomplete. It doesn't explain what the output looks like (e.g., list of customers with scores), how rankings are calculated, or behavioral aspects like safety and performance. Without annotations or output schema, the description should provide more context to compensate, but it falls short, leaving the agent with insufficient information for optimal use.

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 clear descriptions for all parameters (metric, period, limit) including enums and defaults. The description adds no additional meaning beyond what the schema provides—it doesn't explain parameter interactions, ranking algorithms, or edge cases. With high schema coverage, the baseline score of 3 is appropriate as 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 '優良顧客ランキングを取得します' (Get top customer rankings) states a clear verb ('取得します' - get) and resource ('優良顧客ランキング' - top customer rankings), but it's somewhat vague about what constitutes 'top' and doesn't distinguish from sibling tools like get_customer_activity, get_customer_details, or get_customer_segments. It provides basic purpose but lacks specificity about ranking criteria beyond what the schema reveals.

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 no guidance on when to use this tool versus alternatives. With siblings like get_customer_activity (activity tracking), get_customer_details (individual details), and get_customer_segments (segmentation), there's no indication that this tool is specifically for ranking customers by metrics like rentals or spending over time periods. Usage is implied only through the tool name and description, not explicitly stated.

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