Ludus FastMCP

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool retrieves API key information but doesn't specify whether this requires admin permissions, if the key is masked or full, rate limits, or error handling (e.g., for invalid users). For a tool accessing sensitive credentials, this is a significant gap in transparency.

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 appropriately concise with three sentences: a purpose statement, parameter explanation, and return note. It's front-loaded with the main action. However, the 'Args:' and 'Returns:' sections could be integrated more smoothly, and some redundancy exists (e.g., repeating 'API key'), but overall it's efficient.

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 moderate complexity (retrieving sensitive data), no annotations, and an output schema (which handles return values), the description is minimally adequate. It covers purpose and parameters but lacks critical behavioral details like security implications or usage context. With output schema reducing the need to explain returns, it's borderline viable but incomplete for safe operation.

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 1 parameter with 0% description coverage, so the schema provides no semantic context. The description adds minimal value by noting 'user_id: User ID to get API key for', which clarifies the parameter's purpose but doesn't specify format (e.g., numeric vs. string) or constraints. This meets the baseline for low schema coverage but doesn't fully compensate.

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 API key for a user.' It specifies the verb ('Get') and resource ('API key for a user'), making the action unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'get_user' or 'rotate_credentials', which could involve similar user-related operations, so it doesn't reach the highest score.

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. It doesn't mention prerequisites (e.g., user existence or permissions), exclusions, or related tools like 'get_user' for general user info or 'rotate_credentials' for key management. Without such context, the agent lacks clear usage direction.

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