Ludus FastMCP

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions 'power off' (destructive action) and 'admin only' restriction for user_id, but doesn't address important behaviors like: whether this is reversible, error handling for invalid VM names, concurrency limits, or what happens if some VMs fail while others succeed. The description provides basic safety context but lacks comprehensive behavioral details.

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 well-structured with clear sections (purpose, args, returns) and uses minimal words. The first sentence states the core purpose, followed by parameter explanations. However, the 'Returns' section is vague ('Results for each VM') and could be more specific without adding much length.

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?

For a destructive batch operation with 2 parameters, 0% schema coverage, no annotations, and no output schema, the description is inadequate. It doesn't explain the return format, error conditions, side effects, or important behavioral constraints. The agent would struggle to use this tool correctly without trial and error or additional documentation.

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?

With 0% schema description coverage, the schema provides no parameter documentation. The description adds basic semantics: 'vm_names: List of VM names to power off' and 'user_id: Optional user ID (admin only)'. This covers the purpose of both parameters but lacks format details (e.g., VM name format, user ID format) and doesn't explain what happens with null user_id. The description compensates partially but not fully for the schema coverage gap.

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 action ('power off multiple VMs in parallel') and resource ('VMs'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from its sibling 'batch_power_on_hosts' beyond the opposite action, nor does it mention how it differs from 'power_off_range' which appears to operate on ranges rather than individual VMs.

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 minimal guidance on when to use this tool. It mentions 'admin only' for the optional user_id parameter, but doesn't explain when to use this versus 'power_off_range' (for entire ranges) or 'batch_power_on_hosts' (for the opposite operation). No explicit alternatives or exclusions are provided.

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