gmail_discover

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safe, repeatable nature is covered. The description adds that this reveals hidden tools and enumerates the revealed op catalog, which is useful context. However, listing destructive-sounding ops (trash, delete, send) without clarifying they belong to the revealed tools rather than this tool invites confusion.

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 purpose is front-loaded, which is good, but the long enumerated ops list is noisy and the trailing fragment '57 generated ops: users.' reads as truncated/unclear. The core message survives, but the tail does not earn its space.

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 discovery tool with no output schema, the description conveys the gist (a catalog of ops) but leaves the return shape and the meaning of the truncated 'users' fragment unclear. It is adequate but incomplete for an agent trying to act on the result.

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?

There is one optional parameter with 100% schema coverage ('Filter keyword'). The description adds no syntax or format detail about the query filter beyond the schema, so baseline 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?

States a specific verb+resource: it 'lists the catalog and reveals its hidden tools' for gmail, which is clear and actionable. It does not explicitly differentiate itself from sibling discovery tools like discover_all or calendar_discover, but the gmail scoping is unambiguous.

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?

'call first, then call the tool by name' gives a clear sequencing instruction for when to use this tool. It stops short of naming an alternative (e.g., discover_all vs gmail_discover) or stating exclusions, so it isn't a full 5.

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