gmail_watch_start

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

Annotations cover the safety profile (non-read-only, non-destructive, non-idempotent), and the description adds genuinely new traits: ownership/permission requirement on the Pub/Sub topic, the fact that operations are audited, and that watches expire and must be renewed. It stops short of stating the expiration window or whether re-calling replaces an existing watch (relevant given idempotentHint=false).

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?

Four terse sentences, front-loaded with the what/where, followed by prerequisites and lifecycle advice. No sentence is padding; 'Audited.' is terse but carries real 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?

Adequate for a two-parameter mutation with annotations covering safety, but it omits the expiration duration, what the call returns (expiration/historyId), and re-invocation behavior. With no output schema, the description should hint at the returned watch state for an agent to manage renewal.

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 both parameters are already documented, including the projects/PROJECT/topics/TOPIC format. The description reinforces that topic_name is required and must be owned, but says nothing about label_ids (the INBOX-default scope filter), so it adds only marginal value.

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?

Names a specific verb ('Starts') and resource ('Gmail push notifications to a Cloud Pub/Sub topic'), and even cites the underlying API method (users.watch). It implicitly contrasts with the sibling gmail_watch_stop but never names it explicitly, so differentiation relies on the agent inferring from 'Starts'.

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?

'Requires a topicName you own' and 'Renew before expiration' give clear prerequisites and lifecycle context for when to call it. It does not explicitly name gmail_watch_stop as the counterpart for teardown or state what happens if a watch already exists.

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