List who a doc is shared with

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

With no annotations, the description carries the full burden and does an excellent job. It reveals the structure of each entry (subject), explains the meaning of allowFileDiscovery for non-email subjects, and discloses that a doc may already have a domain grant by default. This is rich behavioral context beyond the basic 'list' operation.

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 four sentences long but each sentence adds value: the first states the core purpose, the second explains the subject field format, the third clarifies allowFileDiscovery, and the fourth covers an edge case. It is front-loaded and free of filler.

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 there is no output schema, the description must explain the return format. It does so thoroughly by describing entry fields, special subject values, the allowFileDiscovery behavior, and the default domain grant caveat. This is a complete picture for a listing tool with no additional schema support.

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 50% (account is described, documentId is not). The description adds no parameter-specific guidance, leaving documentId's meaning to be inferred from the tool name. For a required parameter, this is a meaningful gap that the description does not fill.

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 verb 'List' and the resource 'permissions on a Google Doc', specifying the scope (people, groups, domain, anyone-with-link) and that roles are included. It distinguishes itself from sibling sharing tools like share_doc and unshare_doc by focusing on reading the current state.

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 frames the tool as a read-only inspection tool but does not explicitly name alternatives or state when-not-to-use. It provides useful context, such as the note about Workspace domain grants, which helps the user anticipate unexpected results and clarifies the tool's purpose in an audit workflow.

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