List drafts

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, lowering the bar. The description adds valuable behavior beyond annotations: it returns only envelope fields rather than full content, supports Gmail query syntax, and paginates with nextPageToken, which helps the agent know exactly what to expect.

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?

Two sentences with no filler, front-loading the core purpose and return shape before adding usage details. Every clause contributes: scope, fields returned, exclusions, query syntax, and pagination.

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 simple read-only listing tool, the description is complete: it covers return fields, the notable absence of subjects, the query filter mechanism, and pagination. There is no output schema, but the description supplies the key return information an agent needs, and the annotations already cover safety and idempotency.

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%, so the schema fully documents query, page_size, and page_token. The description mentions query filtering and pagination but does not add meaning beyond what the schema already provides, so the baseline 3 is appropriate.

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 an unambiguous verb+resource ('Lists the mailbox's drafts') and specifies the return shape (draft id, message id, threadId). It explicitly differentiates from the sibling get_draft by noting it returns no subjects and pointing to that tool for full detail, so an agent can distinguish it without opening schemas.

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?

Provides clear operational context: query filtering with Gmail syntax and pagination via page_token are described. It gives an exclusion ('no subjects — read one with get_draft'), though it does not systematically contrast with list_messages or list_threads, so it falls just short of fully explicit when/when-not guidance.

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