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

Annotations only declare readOnlyHint, but the description adds real behavioral context: sends only occur inside the window, empty active_days means outreach is paused, a closed window is expected rather than a failure, and the window is user-edited under Settings with no tool able to change it.

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?

Front-loads the one-line purpose, then rationale, then a structured returns block. The XML-style tags are slightly heavier than plain prose, but every sentence carries information an agent needs and nothing is padded.

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?

With no output schema, the description compensates by enumerating every returned field (open_now, window_start, window_end, active_days, timezone) with formats and the null legacy case. Nothing an agent needs to interpret or act on the result is missing.

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% and the single optional parameter (on_behalf_of) is fully documented in the schema, including how to obtain the value from list_agency_clients. The description adds nothing about it, so the 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 resource and the exact fact it returns: the account's outreach activity window plus whether it is open right now. It also implicitly separates itself from queue-management siblings by telling the agent this is the diagnostic to consult when a queue looks idle.

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?

Explicitly names the triggering situation ('when a queue looks idle, check this before telling the user something is broken') and the negative case ('a closed window ... is a normal hold, not a failure'). It even states a constraint on other tools: a send cannot be moved into a closed window.

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