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

Annotations already flag a non-read-only, open-world, idempotent, non-destructive call, and the description adds real behavior beyond that: the notification is delivered as a message to the web mailbox, and the watch expires after 12 hours. It stops short of saying whether it fires once per turn for the whole window or only on the next turn.

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?

One sentence, front-loaded with the resource and scope, ending with the delivery mechanism and duration. No 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?

For a two-parameter tool with no output schema, the description covers scope, outcome channel, and expiry. It leaves open how a watch is identified or cancelled and whether the notification repeats on each turn, which an agent would need in edge cases.

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 coverage is 100%, so the baseline is 3, but the description earns an extra point by clarifying that 'target' is restricted to a single session within the caller's visibility scope (own, team, or a sharing contact), which constrains the handle/session string in ways the schema alone does not.

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 gives a specific verb (watch) plus the resource (one session) and the outcome (a message in the web mailbox when the session finishes its turn). It is clearly distinguishable from siblings like connect_send or connect_inbox, though it never names an alternative explicitly.

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 states an eligibility rule for what may be watched (yours, your team's, a contact's that shares sessions) and a lifetime of 12 hours, which implies usage but does not say when to pick this over connect_message_status or connect_inbox, nor what to do if the target is out of scope.

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