List or cancel scheduled WhatsApp messages

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, so the safe/idempotent profile is covered. The description adds genuine context beyond that: list ordering (waiting soonest first, then the week's sent/missed/failed/cancelled) and the recency window, plus an explicit directive to surface missed/failed messages. It stops short of stating permission requirements or what happens if the cancel window has passed.

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 dense sentences front-load the primary action, and the closing instruction ('Tell the user about every missed or failed one') is a behavioral requirement an agent genuinely needs. No filler or restatement of the title.

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 an output schema present, return values need not be explained, and the description adequately covers both the list and cancel branches of the enum action. Minor gaps remain around the limit parameter and error behavior for a cancel attempted too late, but nothing essential to correct invocation 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 coverage is 60%, and the description reinforces schedule_id's origin (from the list or confirm_send) and the meaning of the closed-message set, which matches the schema's own include_closed description. The limit parameter (default 50, max 100) is never mentioned, so the description does not fully compensate for the coverage gap. Baseline 3 is appropriate when the schema carries most parameter meaning.

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 states a specific resource (the account's scheduled messages) and two concrete verbs (list, cancel), and it explicitly distinguishes itself from the sibling tools send_message and confirm_send that handle scheduling. An agent can identify this tool's role without inspecting the schema.

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 names the alternative workflow for scheduling (send_message with send_at, then confirm_send) and the condition that selects it, plus the constraint that cancellation must happen 'before it goes.' Use vs. alternative is unambiguous.

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