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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered structurally. The description adds genuinely non-obvious behavior beyond that: a hard 200-name cap, exclusion of hidden folders and symlinks, and an unusual auth requirement (account-bound computer:write OAuth plus prompted local owner approval). It does not say what happens when more than 200 entries exist, but the added context is substantial.

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 short sentences, front-loaded with the scope and cap, then the alternative, then the prerequisites — no filler. The auth sentence is dense with jargon but each clause carries real operational meaning, so almost nothing could be cut without losing information.

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 two-parameter read-only listing tool with no output schema, the description covers scope, exclusions, the size cap, an alternative route, and auth prerequisites. The only meaningful omission is behavior at the 200-entry boundary (truncation vs. error) and the exact return shape, which is a modest gap rather than a blocker.

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 100%, and the schema already enumerates the allowed areas, notes 'no arbitrary filesystem roots', and documents subpath as a relative child directory. The description's phrase 'one selected managed home area/subdirectory' only restates that, adding no syntax, depth limit, or path-format guidance beyond the schema, so the baseline of 3 applies.

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 opens with a specific verb+resource+scope: 'List up to 200 names in one selected managed home area/subdirectory', and immediately constrains what is excluded ('no hidden folders or symlinks'). It also names the sibling that covers the restricted workspace, so an agent can distinguish exza_list_home_files from exza_list_workspace_files without opening either 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?

It gives a clear positive condition (listing a managed home area/subdirectory) and an explicit exclusion with a named alternative for the restricted EXZA workspace. It does not route the agent away from adjacent siblings such as exza_search_home_files, exza_list_external_home_folder, or exza_list_home_trash, so the alternatives coverage is partial rather than complete.

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