Katzilla MCP

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

Annotations already indicate read-only, non-destructive, idempotent, and open-world behavior. The description adds valuable context beyond annotations by disclosing the data source, update frequency, and detailed return structure (quality scores, citation with URL, license, SHA-256 hash). This enriches the agent's understanding without contradicting annotations, though it could mention rate limits or authentication needs for a higher score.

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 into two sentences: one for the query purpose and data fields, and another for the source, updates, and return format. Every sentence provides essential information without redundancy, making it front-loaded and appropriately sized for quick comprehension.

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 (querying an external API), rich annotations (read-only, idempotent, etc.), and the presence of an output schema (implied by 'Has output schema: true'), the description is complete. It covers the data source, update frequency, return structure, and audit details, providing sufficient context for an agent to use the tool effectively without needing to explain return values separately.

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 'limit' parameter fully documented in the schema. The description does not add any parameter-specific semantics beyond what the schema provides, such as default behavior or usage tips. Given the high schema coverage, a baseline score of 3 is appropriate, as the description relies on the schema for parameter details.

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 explicitly states the tool's purpose as querying the NASA Exoplanet Archive for confirmed exoplanet data, listing specific fields (name, host star, discovery year, mass, radius). It clearly distinguishes itself from sibling tools by focusing on exoplanet data, unlike other space tools like NASA APOD or asteroids, making the verb+resource combination 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 by specifying the data source (NASA Exoplanet Archive), update frequency (daily), and return format (Katzilla envelope). However, it does not explicitly state when not to use this tool or name alternative tools for similar queries, such as other space-related tools in the sibling list, which limits the score from a perfect 5.

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