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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuinely useful operational context beyond that: the 2,000-entry cap and an explicit truncation indicator, plus the depth ceiling of 10. It does not describe pagination mechanics or the exact truncation field name, keeping it short of a 5.

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 the core action and return shape, then the modifiers, then the hard limit. No filler or restatement of the title.

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?

With no output schema, the description usefully enumerates return fields and the truncation signal, and annotations cover the safety profile. It stops short of explaining the 'hidden' parameter or how to page past a truncated result, which leaves a minor hole for a 6-parameter listing tool.

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 only 17% (path alone), so the description has to carry the load, and it does for most parameters: path default (/workspace), depth semantics ('goes deeper', up to 10), and glob filtering with a concrete pattern example. limit is implied by the 2,000-entry mention, but 'hidden' and 'id' get no explanation, leaving a 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?

States a specific verb and resource ('List a directory in a sandbox') and even enumerates the returned fields (name, path, type, size, mode, modifiedAt), which cleanly separates it from siblings like runtime_sandboxes_files_read, files_write and files_watch. An agent can identify the operation without opening the schema.

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?

Usage is implied rather than stated: it notes the default path (/workspace) and how depth/glob behave, but never says when to use this versus runtime_sandboxes_files_read or files_manage, nor any exclusion. Adequate context, no routing guidance.

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