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

Goes well beyond the readOnlyHint annotation: it discloses ordering (next to go out first), time zone semantics (workspace posting time zone, named per time), that every window is front-loaded with missed posts and reasons, item-count caps per window, and empty-result behavior. These are non-obvious traits an agent could not infer from the schema.

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-loaded with user-question framing, then ordering/return shape, then window definitions, then sibling routing — a sensible progression. The middle sentence is dense with parenthetical caps and could be split for readability, but no sentence is 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?

With no output schema, the description carries the burden of describing returns and does so ('each with its id, time, channel and the start of its copy'), plus empty-case and missed-post behavior. Nothing an agent needs to call and interpret this correctly 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 100% and the enum values are documented there, so the baseline is 3; the description earns extra by defining each window concretely (today = workspace calendar day, week = next 7 days) and giving the per-window caps and the upcoming default. The added semantics are real, though the parameter itself is still only one enum.

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 verb+resource (lists scheduled posts) and immediately frames it with the exact questions it answers, then pins down ordering and item contents. It is clearly distinguishable from list_drafts, list_posts_with_metrics, and get_queue_slots, which are named.

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 maps user questions to the tool ('what's going out today?', 'what's coming up?') and names the alternatives for adjacent needs: drafts go to list_drafts, open schedule slots go to get_queue_slots. It also states what it deliberately excludes (no performance numbers), which prevents misuse for analytics questions.

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