mne_list_files

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

With no annotations, the description carries the full burden. It describes the read-only nature ('List'), the directory fallback, and optional pattern filtering. It does not disclose recursion behavior or return format, but the output schema likely covers return details, and the described behavior is sufficient for a listing tool.

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 two sentences, front-loaded with the core action. It efficiently lists supported file extensions inline without being verbose, and every sentence adds value. No redundant or filler wording.

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 simple file-listing tool, the description covers what files are listed, where it looks by default, and the optional filtering. It could mention recursion or absolute paths, but the presence of an output schema likely covers return structure, making this complete enough for typical use.

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?

Schema description coverage is 0%, so the description must explain parameters. It explicitly mentions the glob pattern and defaults for directory, giving meaning to both parameters beyond their bare schema definitions. It does not detail glob syntax, but the mention of 'pattern' is enough context.

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 uses a specific verb+resource: 'List neurophysiology data files' and enumerates common formats, clearly distinguishing this tool from processing/plotting siblings. It states the directory scope and optional glob pattern, leaving no ambiguity about its function.

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 gives context by mentioning the default directory (MNE_MCP_DATA_DIR / current dir) and optional glob pattern, implying use cases like discovering available data files. However, it does not explicitly state when to use this tool versus alternatives, nor when not to use it.

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