List files

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

Annotations already declare read-only/idempotent/non-destructive, so the bar is lower. The description adds genuinely useful behavior beyond them: a 100-item page cap, path sorting, and the nextCursor paging loop, which the agent cannot infer from the annotations alone.

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?

Three tight sentences, front-loaded with what the tool is and its limits, then the return shape, then pagination. No filler and nothing key buried at the end.

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 a rich output schema, the description need not restate return values, yet it still names the key fields (uri, name, mimeType) that matter for chaining into read_file, and fully covers the one pagination parameter. Nothing needed to call it correctly is missing.

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 coverage is 100%, so cursor is already documented, but the description goes further by explaining the loop semantics ('When nextCursor is returned, call again with it for the next page') and that the cursor is omitted for the first page, which is more than the schema conveys.

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?

States a specific verb (Lists) and resource (the files this server shares), plus scope constraints (read-only, up to 100 per call, sorted by path). It is clearly distinguishable from the only sibling read_file, which consumes the uris this tool returns.

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?

Implies the discovery-then-read workflow by telling the agent each file has a uri 'to pass to read_file', and explains pagination handling explicitly. It does not spell out when NOT to use it (e.g., direct path access), but the context is clear enough to select correctly.

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