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. While it mentions that 'user_id' is 'admin only', it doesn't describe other critical behaviors: whether this is a read-only operation (likely not, as it captures traffic), what permissions are needed beyond admin status, whether it affects VM performance, what happens if capture fails, or any rate limits. For a tool with potential performance impact and admin requirements, this is insufficient.

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 only essential sentences. The opening statement is front-loaded with the core purpose. However, the Args section could be more concise by integrating some details into the schema descriptions, and the Returns statement is somewhat vague ('Traffic capture result with download link').

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 complexity (network capture tool with admin requirements), no annotations, and an output schema (implied by 'Has output schema: true'), the description is moderately complete. It covers parameters well but lacks behavioral context (permissions, performance impact, error handling). The output schema existence means it doesn't need to detail return values, but more operational guidance would help.

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 description compensates well by explaining all 5 parameters in the Args section. It clarifies that 'vm_name' is required, 'interface' defaults to 'eth0', 'duration' is in seconds, 'filter' is an optional BPF expression, and 'user_id' is admin-only. This adds significant meaning beyond the bare schema, though it could provide more detail on BPF filter syntax or interface options.

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 captures network traffic on a VM, specifying the verb 'capture' and resource 'network traffic on a VM'. It distinguishes from siblings like 'diagnose_network_issues' or 'test_network_connectivity' by focusing on active traffic capture rather than diagnostics or connectivity testing. However, it doesn't explicitly differentiate from all siblings, leaving some ambiguity about when to choose this over other network-related tools.

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 many sibling tools like 'diagnose_network_issues', 'get_network_topology', and 'test_network_connectivity', there's no indication of when network traffic capture is appropriate versus other network operations. No prerequisites, exclusions, or alternative tools are mentioned.

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