NEXO Brain

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds useful context: the operation 'survives restarts' (indicating persistence) and that it's for 'FTS5 search indexing' (specifying the indexing system). However, it doesn't cover critical aspects like permissions needed, error conditions, rate limits, or what 'register' entails beyond persistence. The description partially compensates for missing annotations but leaves gaps.

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 and concise. The first sentence states the core purpose and key behavior. The 'Args:' section efficiently documents each parameter without redundancy. Every sentence earns its place, and information is front-loaded for quick understanding.

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 (4 parameters, no annotations, but with an output schema), the description is mostly complete. It covers purpose, persistence, and parameter semantics thoroughly. The output schema likely handles return values, so the description doesn't need to explain them. However, it lacks usage guidelines and some behavioral details (e.g., error handling), which slightly reduces completeness.

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 schema description coverage is 0%, so the description must fully compensate. It does so effectively: it explains all 4 parameters with clear semantics—'path' as an absolute directory path, 'dir_type' with allowed values ('code' or 'md'), 'patterns' as glob patterns for code type only, and 'notes' as a description. This adds significant value beyond the bare schema, making parameter usage understandable.

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: 'Register a new directory for FTS5 search indexing. Survives restarts.' It specifies the verb ('register'), resource ('directory'), and key behavior ('survives restarts'). However, it doesn't explicitly differentiate from its sibling 'nexo_index_remove_dir' or other indexing tools, which prevents a perfect 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, when not to use it, or refer to related tools like 'nexo_index_dirs' for listing or 'nexo_index_remove_dir' for removal. Usage is implied by the purpose statement but lacks explicit context.

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